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19-3447; Rev 0; 10/04
KIT ATION EVALU ABLE AVAIL
14-Bit, 95Msps, 3.3V ADC
General Description Features
Direct IF Sampling Up to 400MHz Excellent Dynamic Performance 74.2dB/72.1dB SNR at fIN = 3MHz/175MHz 88.4dBc/74.7dBc SFDR at fIN = 3MHz/175MHz Low Noise Floor: 74.7dBFS 3.3V Low-Power Operation 465mW (Single-Ended Clock Mode) 497mW (Differential Clock Mode) 300W (Power-Down Mode) Fully Differential or Single-Ended Analog Input Adjustable Full-Scale Analog Input Range 0.35V to 1.10V Common-Mode Reference CMOS-Compatible Outputs in Two's Complement or Gray Code Data-Valid Indicator Simplifies Digital Interface Data Out-of-Range Indicator Miniature, 6mm x 6mm x 0.8mm 40-Pin Thin QFN Package with Exposed Paddle Evaluation Kit Available (Order MAX12555EVKIT)
MAX12555
The MAX12555 is a 3.3V, 14-bit, 95Msps analog-to-digital converter (ADC) featuring a fully differential wideband track-and-hold (T/H) input amplifier, driving a low-noise internal quantizer. The analog input stage accepts singleended or differential signals. The MAX12555 is optimized for high dynamic performance, low power, and small size. Excellent dynamic performance is maintained from baseband to input frequencies of 175MHz and beyond, making the MAX12555 ideal for intermediatefrequency (IF) sampling applications. Powered from a single 3.3V supply, the MAX12555 consumes only 497mW while delivering a typical 72.1dB signal-to-noise ratio (SNR) performance at a 175MHz input frequency. In addition to low operating power, the MAX12555 features a 300W power-down mode to conserve power during idle periods. A flexible reference structure allows the MAX12555 to use the internal 2.048V bandgap reference or accept an externally applied reference. The reference structure allows the full-scale analog input range to be adjusted from 0.35V to 1.10V. The MAX12555 provides a common-mode reference to simplify design and reduce external component count in differential analog input circuits. The MAX12555 supports either a single-ended or differential input clock. Wide variations in the clock duty cycle are compensated with the ADC's internal dutycycle equalizer (DCE). ADC conversion results are available through a 14-bit, parallel, CMOS-compatible output bus. The digital output format is pin selectable to be either two's complement or Gray code. A data-valid indicator eliminates external components that are normally required for reliable digital interfacing. A separate digital power input accepts a wide 1.7V to 3.6V supply, allowing the MAX12555 to interface with various logic levels. The MAX12555 is available in a 6mm x 6mm x 0.8mm, 40-pin thin QFN package with exposed paddle (EP), and is specified for the extended industrial (-40C to +85C) temperature range. See the Pin-Compatible Versions table for a complete family of 14-bit and 12-bit high-speed ADCs.
Ordering Information
PART* MAX12555ETL MAX12555ETL+ PIN-PACKAGE 40 Thin QFN 40 Thin QFN PKG CODE T4066-3 T4066-3
+Denotes lead-free package. *All devices specified over the -40C to +85C operating range.
Pin-Compatible Versions
PART MAX12555 MAX12554 MAX12553 MAX19538 MAX1209 MAX1211 MAX1208 MAX1207 MAX1206 SAMPLING RATE (Msps) 95 80 65 95 80 65 80 65 40 RESOLUTION (BITS) 14 14 14 12 12 12 12 12 12 TARGET APPLICATION IF/Baseband IF/Baseband IF/Baseband IF/Baseband IF IF Baseband Baseband Baseband
Applications
IF and Baseband Communication Receivers Cellular, Point-to-Point Microwave, HFC, WLAN Medical Imaging Including Positron Emission Tomography (PET) Video Imaging Portable Instrumentation Low-Power Data Acquisition
Pin Configuration appears at end of data sheet. ________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
14-Bit, 95Msps, 3.3V ADC MAX12555
ABSOLUTE MAXIMUM RATINGS
VDD to GND ...........................................................-0.3V to +3.6V OVDD to GND........-0.3V to the lower of (VDD + 0.3V) and +3.6V INP, INN to GND ...-0.3V to the lower of (VDD + 0.3V) and +3.6V REFIN, REFOUT, REFP, REFN, COM to GND................-0.3V to the lower of (VDD + 0.3V) and +3.6V CLKP, CLKN, CLKTYP, G/T, DCE, PD to GND ........-0.3V to the lower of (VDD + 0.3V) and +3.6V D13-D0, DAV, DOR to GND....................-0.3V to (OVDD + 0.3V) Continuous Power Dissipation (TA = +70C) 40-Pin Thin QFN 6mm x 6mm x 0.8mm (derated 26.3mW/C above +70C)........................2105.3mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering 10s) ..................................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VDD = 3.3V, OVDD = 1.8V, GND = 0, REFIN = REFOUT (internal reference), VIN = -0.5dBFS, CLKTYP = high, DCE = high, PD = low, G/T = low, fCLK = 95MHz (50% duty cycle, 1.4VP-P square wave), TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER DC ACCURACY (Note 2) Resolution Integral Nonlinearity Differential Nonlinearity Offset Error Gain Error ANALOG INPUT (INP, INN) Differential Input Voltage Range Common-Mode Input Voltage Input Capacitance (Figure 3) CONVERSION RATE Maximum Clock Frequency Minimum Clock Frequency Data Latency Figure 6 8.0 fCLK 95 5 MHz MHz Clock cycles dBFS CPAR CSAMPLE Fixed capacitance to ground Switched capacitance VDIFF Differential or single-ended inputs 1.024 VDD / 2 2 4.5 V V pF INL DNL fIN = 3MHz fIN = 3MHz VREFIN = 2.048V VREFIN = 2.048V 14 1.6 0.65 0.1 0.35 0.78 5.3 Bits LSB LSB %FS %FS SYMBOL CONDITIONS MIN TYP MAX UNITS
DYNAMIC CHARACTERISTICS (Differential Inputs) (Note 2) Small-Signal Noise Floor SSNF Input at less than -35dBFS fIN = 3MHz at -0.5dBFS (Notes 3, 4) Signal-to-Noise Ratio SNR fIN = 47.5MHz at -0.5dBFS fIN = 70MHz at -0.5dBFS fIN = 175MHz at -0.5dBFS (Notes 3, 4) fIN = 3MHz at -0.5dBFS (Notes 3, 4) Signal-to-Noise and Distortion SINAD fIN = 47.5MHz at -0.5dBFS fIN = 70MHz at -0.5dBFS fIN = 175MHz at -0.5dBFS (Notes 3, 4) 64.0 66.9 66.7 67.6 -74.7 74.2 73.8 73.6 72.1 73.8 73.5 72.5 69.8 dB dB
2
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14-Bit, 95Msps, 3.3V ADC
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 3.3V, OVDD = 1.8V, GND = 0, REFIN = REFOUT (internal reference), VIN = -0.5dBFS, CLKTYP = high, DCE = high, PD = low, G/T = low, fCLK = 95MHz (50% duty cycle, 1.4VP-P square wave), TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER SYMBOL CONDITIONS fIN = 3MHz at -0.5dBFS (Notes 3, 4) Spurious-Free Dynamic Range SFDR fIN = 47.5MHz at -0.5dBFS fIN = 70MHz at -0.5dBFS fIN = 175MHz at -0.5dBFS (Notes 3, 4) fIN = 3MHz at -0.5dBFS Total Harmonic Distortion THD fIN = 47.5MHz at -0.5dBFS fIN = 70MHz at -0.5dBFS fIN = 175MHz at -0.5dBFS fIN = 3MHz at -0.5dBFS Second Harmonic HD2 fIN = 47.5MHz at -0.5dBFS fIN = 70MHz at -0.5dBFS fIN = 175MHz at -0.5dBFS fIN = 3MHz at -0.5dBFS Third Harmonic HD3 fIN = 47.5MHz at -0.5dBFS fIN = 70MHz at -0.5dBFS fIN = 175MHz at -0.5dBFS fIN1 = 68.5MHz at -7dBFS fIN2 = 71.5MHz at -7dBFS fIN1 = 172.5MHz at -7dBFS fIN2 = 177.5MHz at -7dBFS fIN1 = 68.5MHz at -7dBFS fIN2 = 71.5MHz at -7dBFS fIN1 = 172.5MHz at -7dBFS fIN2 = 177.5MHz at -7dBFS Two-Tone Spurious-Free Dynamic Range Aperture Delay Aperture Jitter Output Noise Overdrive Recovery Time fIN1 = 68.5MHz at -7dBFS fIN2 = 71.5MHz at -7dBFS fIN1 = 172.5MHz at -7dBFS fIN2 = 177.5MHz at -7dBFS Figure 4 Figure 4 INP = INN = COM 10% beyond full scale 67.1 MIN 73.5 TYP 88.4 86.9 80.5 74.7 -85.1 -84.7 -79.0 -73.6 -89 -92 -91 -82 -92 -93 -81 -75 -79 dBc -75 -80 dBc -76 80 dBc 76 1.2 <0.2 1.07 1 ns psRMS LSBRMS Clock cycles dBc dBc -66.1 -72.8 dBc dBc MAX UNITS
MAX12555
Intermodulation Distortion
IMD
Third-Order Intermodulation
IM3
SFDRTT
tAD tAJ nOUT
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3
14-Bit, 95Msps, 3.3V ADC MAX12555
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 3.3V, OVDD = 1.8V, GND = 0, REFIN = REFOUT (internal reference), VIN = -0.5dBFS, CLKTYP = high, DCE = high, PD = low, G/T = low, fCLK = 95MHz (50% duty cycle, 1.4VP-P square wave), TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER REFOUT Output Voltage COM Output Voltage Differential-Reference Output Voltage REFOUT Load Regulation REFOUT Temperature Coefficient REFOUT Short-Circuit Current TCREF Short to VDD--sinking Short to GND--sourcing VREFIN VREFP VREFN VCOM VREF (VDD / 2) + (VREFIN x 3/8) (VDD / 2) - (VREFIN x 3/8) VDD / 2 VREF = VREFP - VREN = VREFIN x 3/4 1.60 1.454 25 >50 VCOM VDD / 2 VREFP - VCOM VREFN - VCOM VREF IREFP IREFN ICOM VREF = VREFP - VREFN = VREFIN x 3/4 VREFP = 2.418V VREFN = 0.882V VCOM = 1.650V 1.65 0.768 -0.768 1.536 1.4 1.0 1.0 13 6 0.8 x VDD 0.2 x VDD 0.2 SYMBOL VREFOUT VCOM VREF VDD / 2 VREF = VREFP - VREFN = VREFIN x 3/4 -1.0mA < IREFOUT < +0.1mA CONDITIONS MIN 1.980 TYP 2.048 1.65 1.536 35 +50 0.24 2.1 2.048 2.418 0.882 1.65 1.70 1.604 MAX 2.066 UNITS V V V mV/mA ppm/C mA
INTERNAL REFERENCE (REFIN = REFOUT; VREFP, VREFN, and VCOM are generated internally)
BUFFERED EXTERNAL REFERENCE (REFIN driven externally; VREFIN = 2.048V, VREFP, VREFN, and VCOM are generated internally) REFIN Input Voltage REFP Output Voltage REFN Output Voltage COM Output Voltage Differential-Reference Output Voltage Differential-Reference Temperature Coefficient REFIN Input Resistance UNBUFFERED EXTERNAL REFERENCE (REFIN = GND; VREFP, VREFN, and VCOM are applied externally) COM Input Voltage REFP Input Voltage REFN Input Voltage Differential-Reference Input Voltage REFP Sink Current REFN Source Current COM Sink Current REFP, REFN Capacitance COM Capacitance CLOCK INPUTS (CLKP, CLKN) Single-Ended Input High Threshold Single-Ended Input Low Threshold Minimum Differential Input Voltage Swing VIH VIL CLKTYP = GND, CLKN = GND CLKTYP = GND, CLKN = GND CLKTYP = high V V VP-P V V V V mA mA mA pF pF V V V V V ppm/C M
4
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14-Bit, 95Msps, 3.3V ADC
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 3.3V, OVDD = 1.8V, GND = 0, REFIN = REFOUT (internal reference), VIN = -0.5dBFS, CLKTYP = high, DCE = high, PD = low, G/T = low, fCLK = 95MHz (50% duty cycle, 1.4VP-P square wave), TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER Differential Input Common-Mode Voltage Input Resistance Input Capacitance RCLK CCLK 0.8 x OVDD 0.2 x OVDD VIH = OVDD VIL = 0 CDIN D13-D0, DOR, ISINK = 200A DAV, ISINK = 600A D13-D0, DOR, ISOURCE = 200A Output-Voltage High VOH DAV, ISOURCE = 600A Tri-State Leakage Current D13-D0, DOR Tri-State Output Capacitance DAV Tri-State Output Capacitance POWER REQUIREMENTS Analog Supply Voltage Digital Output Supply Voltage VDD OVDD Normal operating mode, fIN = 175MHz at -0.5dBFS, CLKTYP = GND, single-ended clock Analog Supply Current IVDD Normal operating mode, fIN = 175MHz at -0.5dBFS, CLKTYP = OVDD, differential clock Power-down mode clock idle, PD = OVDD 3.15 1.7 3.3 1.8 3.60 VDD + 0.3V V V ILEAK COUT CDAV (Note 5) (Note 5) (Note 5) 3 6 OVDD 0.2 V OVDD 0.2 5 A pF pF 5 0.2 0.2 5 5 SYMBOL CONDITIONS CLKTYP = high Figure 5 MIN TYP VDD / 2 5 2 MAX UNITS V k pF
MAX12555
DIGITAL INPUTS (CLKTYP, DCE, G/T, PD) Input High Threshold Input Low Threshold Input Leakage Current Input Capacitance VIH VIL V V A pF
DIGITAL OUTPUTS (D13-D0, DAV, DOR) Output-Voltage Low VOL V
141 mA 150.6 0.1 165
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5
14-Bit, 95Msps, 3.3V ADC MAX12555
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 3.3V, OVDD = 1.8V, GND = 0, REFIN = REFOUT (internal reference), VIN = -0.5dBFS, CLKTYP = high, DCE = high, PD = low, G/T = low, fCLK = 95MHz (50% duty cycle, 1.4VP-P square wave), TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER SYMBOL CONDITIONS Normal operating mode, fIN = 175MHz at -0.5dBFS, CLKTYP = GND, single-ended clock Analog Power Dissipation PDISS Normal operating mode, fIN = 175MHz at -0.5dBFS, CLKTYP = OVDD, differential clock Power-down mode clock idle, PD = OVDD Normal operating mode, fIN = 175MHz at -0.5dBFS, OVDD = 1.8V, CL 5pF Power-down mode clock idle, PD = OVDD TIMING CHARACTERISTICS (Figure 6) Clock Pulse-Width High Clock Pulse-Width Low Data-Valid Delay Data Setup Time Before Rising Edge of DAV Data Hold Time After Rising Edge of DAV Wake-Up Time from Power-Down tCH tCL tDAV tSETUP tHOLD tWAKE CL = 5pF (Note 6) CL = 5pF (Notes 6, 7) CL = 5pF (Notes 6, 7) VREFIN = 2.048V 5.5 4.0 10 5.2 5.2 5.2 ns ns ns ns ns ms MIN TYP 465 mW 497 0.3 10.2 8 mA A 545 MAX UNITS
Digital Output Supply Current
IOVDD
Note 1: Specifications +25C guaranteed by production test; <+25C guaranteed by design and characterization. Note 2: See definitions in the Parameter Definitions section at the end of this data sheet. Note 3: Limit specifications include performance degradations due to a production test socket. Performance is improved when the MAX12555 is soldered directly to the PC board. Note 4: Due to test-equipment-jitter limitations at 175MHz, 0.15% of the spectrum on each side of the fundamental is excluded from the spectral analysis. Note 5: During power-down, D13-D0, DOR, and DAV are high impedance. Note 6: Digital outputs settle to VIH or VIL. Note 7: Guaranteed by design and characterization.
6
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14-Bit, 95Msps, 3.3V ADC MAX12555
Typical Operating Characteristics
(VDD = 3.3V, OVDD = 1.8V, GND = 0, REFIN = REFOUT (internal reference), VIN = -0.5dBFS, CLKTYP = high, DCE = high, PD = low, G/T = low, fCLK 95MHz (50% duty cycle, 1.4VP-P square wave), TA = +25C, unless otherwise noted.)
SINGLE-TONE FFT PLOT (8192-POINT DATA RECORD)
MAX12555 toc01
SINGLE-TONE FFT PLOT (8192-POINT DATA RECORD)
MAX12555 toc02
SINGLE-TONE FFT PLOT (8192-POINT DATA RECORD)
-10 -20 AMPLITUDE (dBFS) -30 -40 -50 -60 -70 -80 -90 -100 -110 fCLK = 95MHz fIN = 70.00915527MHz AIN = -0.5dBFS SNR = 73.12dB SINAD = 71.50dB THD = -76.6dBc SFDR = 77.8dBc HD3 HD7 HD5 HD2
MAX12555 toc03
0 -10 -20 AMPLITUDE (dBFS) -30 -40 -50 -60 -70 -80 -90 -100 -110 0 5
AMPLITUDE (dBFS)
fCLK = 95MHz fIN = 3.00354004MHz AIN = -0.5dBFS SNR = 73.82dB SINAD = 73.31dB THD = -82.8dBc SFDR = 86.3dBc HD3 HD5 HD7 HD9 HD2
0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110
fCLK = 95MHz fIN = 47.30285645MHz AIN = -0.5dBFS SNR = 73.13dB SINAD = 72.74dB THD = -83.4dBc SFDR = 85.1dBc HD5 HD2
0
10 15 20 25 30 35 40 45 FREQUENCY (MHz)
0
5
10 15 20 25
30 35 40 45
0
5
10 15 20 25
30 35 40 45
FREQUENCY (MHz)
FREQUENCY (MHz)
SINGLE-TONE FFT PLOT (8192-POINT DATA RECORD)
MAX12555 toc04
SINGLE-TONE FFT PLOT (8192-POINT DATA RECORD)
MAX12555 toc05
TWO-TONE FFT PLOT (16,384-POINT DATA RECORD)
-10 -20 AMPLITUDE (dBFS) -30 -40 -50 -60 -70 -80 -90 -100 -110 fCLK = 95MHz fIN1 = 68.49579MHz AIN1 = -6.9dBFS fIN2 = 71.49933MHz AIN2 = -7.0dBFS SFDRTT = 77.9dBc IMD = -76.4dBc IM3 = -77.5dBc 2 x fIN2 + fIN1 2 x fIN1 + fIN2 fIN1 fIN2
MAX12555 toc06
0 -10 -20 AMPLITUDE (dBFS) -30 -40 -50 -60 -70 -80 -90 -100 -110 0 5
AMPLITUDE (dBFS)
fCLK = 95MHz fIN = 174.8895264MHz AIN = -0.5dBFS SNR = 71.29dB SINAD = 68.98dB THD = -72.8dBc SFDR = 74.4dBc HD3 HD5 HD2
0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110
fCLK = 95MHz fIN = 225.010376MHz AIN = -0.5dBFS SNR = 70.67dB SINAD = 67.70dB THD = -70.7dBc SFDR = 72.5dBc HD3 HD2 HD5
0
HD9
HD7
2 x fIN1 + 3 x fIN2 fIN1 + fIN2
10 15 20 25
30 35 40 45
0
5
10 15 20 25
30 35 40 45
0
5
10 15 20 25
30 35 40 45
FREQUENCY (MHz)
FREQUENCY (MHz)
FREQUENCY (MHz)
TWO-TONE FFT PLOT (16,384-POINT DATA RECORD)
MAX12555 toc07
INTEGRAL NONLINEARITY
MAX12555 toc08
DIFFERENTIAL NONLINEARITY
0.8 0.6 0.4 DNL (LSB) 0.2 0 -0.2 -0.4 -0.6 -0.8
MAX12555 toc09
0 -10 -20 AMPLITUDE (dBFS) -30 -40 -50 -60 -70 -80 -90 -100 -110 0 5 fIN1 fIN2
INL (LSB)
fCLK = 95MHz fIN1 = 172.4949MHz AIN1 = -7.0dBFS fIN2 = 177.493MHz AIN2 = -7.0dBFS SFDRTT = 74.6dBc IMD = -73.6dBc IM3 = -74.7dBc 2 x fIN2 + fIN1 2 x fIN1 + fIN2 fIN1 + fIN2
3 2 1 0 -1 -2 -3
1.0
-1.0 0 4096 8192 12288 16384 0 4096 8192 12288 16384 DIGITAL OUTPUT CODE DIGITAL OUTPUT CODE
10 15 20 25
30 35 40 45
FREQUENCY (MHz)
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7
14-Bit, 95Msps, 3.3V ADC MAX12555
Typical Operating Characteristics (continued)
(VDD = 3.3V, OVDD = 1.8V, GND = 0, REFIN = REFOUT (internal reference), VIN = -0.5dBFS, CLKTYP = high, DCE = high, PD = low, G/T = low, fCLK 95MHz (50% duty cycle, 1.4VP-P square wave), TA = +25C, unless otherwise noted.)
SNR, SINAD vs. SAMPLING RATE
MAX12555 toc10
SFDR, -THD vs. SAMPLING RATE
MAX12555 toc11
POWER DISSIPATION vs. SAMPLING RATE
550 POWER DISSIPATION (mW) 500 450 400 350 300 250 200 ANALOG + DIGITAL POWER ANALOG POWER 25 45 65 85 105 125 DIFFERENTIAL CLOCK fIN = 70MHz CL 5pF
MAX12555 toc12
76 fIN = 70MHz 74 72 70 68 66 64 62 60 25 45 65 85 105 SNR SINAD
100 fIN = 70MHz 95 90 SFDR, -THD (dBc) 85 80 75 70 65 60 SFDR -THD 25 45 65 85 105
600
SNR, SINAD (dB)
125
125
fCLK (MHz)
fCLK (MHz)
fCLK (MHz)
SNR, SINAD vs. SAMPLING RATE
MAX12555 toc13
SFDR, -THD vs. SAMPLING RATE
MAX12555 toc14
POWER DISSIPATION vs. SAMPLING RATE
550 POWER DISSIPATION (mW) 500 450 400 350 300 250 200 ANALOG + DIGITAL POWER ANALOG POWER 25 45 65 85 105 125 DIFFERENTIAL CLOCK fIN = 175MHz CL 5pF
MAX12555 toc15 MAX12555 toc18
76 fIN = 175MHz 74 72 70 68 66 64 62 60 25 SNR SINAD 45 65 85 105
100 95 90 SFDR, -THD (dBc) 85 80 75 70 65 60
fIN = 175MHz
600
SNR, SINAD (dB)
SFDR -THD 25 45 65 85 105 125
125
fCLK (MHz)
fCLK (MHz)
fCLK (MHz)
SNR, SINAD vs. ANALOG INPUT FREQUENCY
MAX12555 toc16
SFDR, -THD vs. ANALOG INPUT FREQUENCY
MAX12555 toc17
POWER DISSIPATION vs. ANALOG INPUT FREQUENCY
600 550 POWER DISSIPATION (mW) 500 450 400 350 300 250 200 0 50 100 150 200 250 300 350 400 ANALOG INPUT FREQUENCY (MHz) ANALOG + DIGITAL POWER ANALOG POWER DIFFERENTIAL CLOCK CL 5pF
76 74 72 70 68 66 64 62 60 0 50 SNR SINAD
100 95 90 SFDR, -THD (dBc) 85 80 75 70 65 60 0 50 SFDR -THD
SNR, SINAD (dB)
100 150 200 250 300 350 400
100 150 200 250 300 350 400
ANALOG INPUT FREQUENCY (MHz)
ANALOG INPUT FREQUENCY (MHz)
8
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14-Bit, 95Msps, 3.3V ADC MAX12555
Typical Operating Characteristics (continued)
(VDD = 3.3V, OVDD = 1.8V, GND = 0, REFIN = REFOUT (internal reference), VIN = -0.5dBFS, CLKTYP = high, DCE = high, PD = low, G/T = low, fCLK 95MHz (50% duty cycle, 1.4VP-P square wave), TA = +25C, unless otherwise noted.)
SNR, SINAD vs. ANALOG INPUT AMPLITUDE
MAX12555 toc19
SFDR, -THD vs. ANALOG INPUT AMPLITUDE
MAX12555 toc20
POWER DISSIPATION vs. ANALOG INPUT AMPLITUDE
550 POWER DISSIPATION (mW) 500 450 400 350 300 250 200 0 -40 -35 ANALOG + DIGITAL POWER ANALOG POWER -30 -25 -20 -15 -10 -5 0 DIFFERENTIAL CLOCK fIN = 175MHz CL 5pF
MAX12555 toc21
75 70 65 SNR, SINAD (dB) 60 55 50 45 40 35 30 25 -40 -35 SNR SINAD -30 -25 -20 -15 -10 -5 0 fIN = 175MHz
90 85 80 SFDR, -THD (dBc) 75 70 65 60 55 50 -40 -35 -30 -25 -20 -15 -10 -5 ANALOG INPUT AMPLITUDE (dBFS) SFDR -THD fIN = 175MHz
600
ANALOG INPUT AMPLITUDE (dBFS)
ANALOG INPUT AMPLITUDE (dBFS)
SNR, SINAD vs. ANALOG SUPPLY VOLTAGE
MAX12555 toc22
SFDR, -THD vs. ANALOG SUPPLY VOLTAGE
MAX12555 toc23
POWER DISSIPATION vs. ANALOG SUPPLY VOLTAGE
650 POWER DISSIPATION (mW) 600 550 500 450 400 350 300 ANALOG + DIGITAL POWER ANALOG POWER 2.8 3.0 3.2 AVDD (V) 3.4 3.6 DIFFERENTIAL CLOCK fIN = 175MHz CL 5pF
MAX12555 toc24
74 73 72 SNR, SINAD (dB) 71 70 69 68 67 66 65 64 2.8 3.0 3.2 AVDD (V) 3.4 SNR SINAD fIN = 175MHz
100 95 90 SFDR, -THD (dBc) 85 80 75 70 65 60 SFDR -THD 2.8 3.0 3.2 AVDD (V) 3.4 fIN = 175MHz
700
3.6
3.6
SNR, SINAD vs. DIGITAL SUPPLY VOLTAGE
MAX12555 toc25
SFDR, -THD vs. DIGITAL SUPPLY VOLTAGE
MAX12555 toc26
POWER DISSIPATION vs. DIGITAL SUPPLY VOLTAGE
550 POWER DISSIPATION (mW) 500 450 400 350 300 250 200 ANALOG + DIGITAL POWER ANALOG POWER 1.4 1.8 2.2 2.6 OVDD (V) 3.0 3.4 3.8 DIFFERENTIAL CLOCK fIN = 175MHz CL 5pF
MAX12555 toc27
76 74 72 70 68 66 64 62 60 1.4 SNR SINAD 1.8 2.2 2.6 OVDD (V) 3.0 3.4 fIN = 175MHz
100 95 90 SFDR, -THD (dBc) 85 80 75 70 65 60 SFDR -THD 1.4 1.8 2.2 2.6 OVDD (V) 3.0 3.4 fIN = 175MHz
600
SNR, SINAD (dB)
3.8
3.8
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9
14-Bit, 95Msps, 3.3V ADC MAX12555
Typical Operating Characteristics (continued)
(VDD = 3.3V, OVDD = 1.8V, GND = 0, REFIN = REFOUT (internal reference), VIN = -0.5dBFS, CLKTYP = high, DCE = high, PD = low, G/T = low, fCLK 95MHz (50% duty cycle, 1.4VP-P square wave), TA = +25C, unless otherwise noted.)
SNR, SINAD vs. TEMPERATURE
MAX12555 toc28
SFDR, -THD vs. TEMPERATURE
MAX12555 toc29
POWER DISSIPATION vs. TEMPERATURE
550 500 450 400 350 300 250 200 ANALOG + DIGITAL POWER ANALOG POWER -40 -15 10 35 60 85 DIFFERENTIAL CLOCK fIN = 175MHz CL 5pF
MAX12555 toc30
72 71 70 SNR, SINAD (dB) 69 68 67 66 65 64 63 62 -40 -15 10 35 60 SNR SINAD fIN = 175MHz
100 95 90 SFDR, -THD (dBc) 85 80 75 70 65 60 SFDR -THD -40 -15 10 35 60 fIN = 175MHz
600 ANALOG POWER DISSIPATION (mW)
85
85
TEMPERATURE (C)
TEMPERATURE (C)
TEMPERATURE (C)
OFFSET ERROR vs. TEMPERATURE
0.4 0.3 OFFSET ERROR (%FS) 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 -0.5 -40 -15 10 35 60 85 TEMPERATURE (C) VREFIN = 2.048V
MAX12555 toc31
GAIN ERROR vs. TEMPERATURE
VREFIN = 2.048V 1.5 1.0 GAIN ERROR (%FS) 0.5 0 -0.5 -1.0 -1.5 -2.0 -40 -15 10 35 60 85 TEMPERATURE (C)
MAX12555 toc32
0.5
2.0
10
______________________________________________________________________________________
14-Bit, 95Msps, 3.3V ADC MAX12555
Typical Operating Characteristics (continued)
(VDD = 3.3V, OVDD = 1.8V, GND = 0, REFIN = REFOUT (internal reference), VIN = -0.5dBFS, CLKTYP = high, DCE = high, PD = low, G/T = low, fCLK 95MHz (50% duty cycle, 1.4VP-P square wave), TA = +25C, unless otherwise noted.)
REFERENCE OUTPUT VOLTAGE LOAD REGULATION
MAX12555 toc33
REFERENCE OUTPUT VOLTAGE SHORT-CIRCUIT PERFORMANCE
MAX12555 toc34
REFERENCE OUTPUT VOLTAGE vs. TEMPERATURE
MAX12555 toc35
2.05 2.04 2.03 2.02 VREFOUT (V) +85C
3.5 3.0 2.5 VREFOUT (V) 2.0 1.5 +25C 1.0 +85C
2.039
2.037 VREFOUT (V)
2.01 2.00 1.99 1.98 1.97 1.96 1.95 -2.0
2.035
2.033
-40C +25C
2.031 0.5 0 -40C 2.029 -3.0 -2.0 -1.0 0 1.0 -40 -15 10 35 60 85 IREFOUT SINK CURRENT (mA) TEMPERATURE (C)
-1.5
-1.0
-0.5
0
0.5
IREFOUT SINK CURRENT (mA)
REFP, COM, REFN LOAD REGULATION
MAX12555 toc36
REFP, COM, REFN SHORT-CIRCUIT PERFORMACE
MAX12555 toc37
3.0 VREFP 2.5 2.0 1.5 VREFN 1.0 0.5 0 -2 -1 0 SINK CURRENT (mA) 1 2 INTERNAL REFERENCE MODE AND BUFFERED EXTERNAL REFERENCE MODE VCOM
3.5 3.0 2.5 VOLTAGE (V) 2.0 1.5 1.0 0.5 0 -8 -4 0 4 8 INTERNAL REFERENCE MODE AND BUFFERED EXTERNAL REFERENCE MODE VREFP VREFN VCOM
VOLTAGE (V)
12
SINK CURRENT (mA)
______________________________________________________________________________________
11
14-Bit, 95Msps, 3.3V ADC MAX12555
Pin Description
PIN NAME FUNCTION Positive Reference I/O. The full-scale analog input range is (VREFP - VREFN) x 2/3. Bypass REFP to GND with a 0.1F capacitor. Connect a 1F capacitor in parallel with a 10F capacitor between REFP and REFN. Place the 1F REFP to REFN capacitor as close to the device as possible on the same side of the PC board. Negative Reference I/O. The full-scale analog input range is (VREFP - VREFN) x 2/3. Bypass REFN to GND with a 0.1F capacitor. Connect a 1F capacitor in parallel with a 10F capacitor between REFP and REFN. Place the 1F REFP to REFN capacitor as close to the device as possible on the same side of the PC board. Common-Mode Voltage I/O. Bypass COM to GND with a 2.2F capacitor. Place the 2.2F COM to GND capacitor as close to the device as possible. This 2.2F capacitor can be placed on the opposite side of the PC board and connected to the MAX12555 through a via. Ground. Connect all ground pins and EP together. Positive Analog Input Negative Analog Input Duty-Cycle Equalizer Input. Connect DCE low (GND) to disable the internal duty-cycle equalizer. Connect DCE high (OVDD or VDD) to enable the internal duty-cycle equalizer. Negative Clock Input. In differential clock input mode (CLKTYP = OVDD or VDD), connect the differential clock signal between CLKP and CLKN. In single-ended clock mode (CLKTYP = GND), apply the singleended clock signal to CLKP and connect CLKN to GND. Positive Clock Input. In differential clock input mode (CLKTYP = OVDD or VDD), connect the differential clock signal between CLKP and CLKN. In single-ended clock mode (CLKTYP = GND), apply the singleended clock signal to CLKP and connect CLKN to GND. Clock-Type Definition Input. Connect CLKTYP to GND to define the single-ended clock input. Connect CLKTYP to OVDD or VDD to define the differential clock input. Analog Power Input. Connect VDD to a 3.15V to 3.60V power supply. Bypass VDD to GND with a parallel capacitor combination of 2.2F and 0.1F. Connect all VDD pins to the same potential. Output-Driver Power Input. Connect OVDD to a 1.7V to VDD power supply. Bypass OVDD to GND with a parallel capacitor combination of 2.2F and 0.1F. Data Out-of-Range Indicator. The DOR digital output indicates when the analog input voltage is out of range. When DOR is high, the analog input is beyond its full-scale range. When DOR is low, the analog input is within its full-scale range (Figure 6). CMOS Digital Output Bit 13 (MSB) CMOS Digital Output Bit 12 CMOS Digital Output Bit 11 CMOS Digital Output Bit 10 CMOS Digital Output Bit 9 CMOS Digital Output Bit 8 CMOS Digital Output Bit 7 CMOS Digital Output Bit 6 CMOS Digital Output Bit 5
1
REFP
2
REFN
3 4, 7, 16, 35 5 6 8
COM
GND INP INN DCE
9
CLKN
10
CLKP
11 12-15, 36 17, 34
CLKTYP VDD OVDD
18 19 20 21 22 23 24 25 26 27
DOR D13 D12 D11 D10 D9 D8 D7 D6 D5
12
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14-Bit, 95Msps, 3.3V ADC MAX12555
Pin Description (continued)
PIN 28 29 30 31 32 33 37 38 NAME D4 D3 D2 D1 D0 DAV PD REFOUT CMOS Digital Output Bit 4 CMOS Digital Output Bit 3 CMOS Digital Output Bit 2 CMOS Digital Output Bit 1 CMOS Digital Output Bit 0 (LSB) Data-Valid Output. DAV is a single-ended version of the input clock that is compensated to correct for any input clock duty-cycle variations. DAV is typically used to latch the MAX12555 output data into an external back-end digital circuit. Power-Down Input. Force PD high for power-down mode. Force PD low for normal operation. Internal Reference Voltage Output. For internal reference operation, connect REFOUT directly to REFIN or use a resistive divider from REFOUT to set the voltage at REFIN. Bypass REFOUT to GND with a 0.1F capacitor. Reference Input. In internal reference mode and buffered external reference mode, bypass REFIN to GND with a 0.1F capacitor. In these modes, VREFP - VREFN = VREFIN x 3/4. For unbuffered external reference mode operation, connect REFIN to GND. Output-Format-Select Input. Connect G/T to GND for the two's-complement digital output format. Connect G/T to OVDD or VDD for the Gray code digital output format. Exposed Paddle. The MAX12555 relies on the exposed paddle connection for a low-inductance ground connection. Connect EP to GND to achieve specified performance. Use multiple vias to connect the top-side PC board ground plane to the bottom-side PC board ground plane. FUNCTION
39
REFIN
40
G/T
--
EP
MAX12555
T/H
+
-
FLASH ADC
DAC
INP T/H INN DIGITAL ERROR CORRECTION D13-D0 OUTPUT DRIVERS STAGE 1 STAGE 2 STAGE 9
STAGE 10 END OF PIPE
D13-D0
Figure 1. Pipeline Architecture--Stage Blocks
______________________________________________________________________________________
13
14-Bit, 95Msps, 3.3V ADC MAX12555
CLKP CLKN DCE CLKTYP
CLOCK GENERATOR AND DUTY-CYCLE EQUALIZER
MAX12555
VDD GND
BOND WIRE INDUCTANCE 1.5nH INP
VDD
MAX12555
OVDD 14-BIT PIPELINE ADC D13-D0 DAV DOR
CPAR 2pF
*CSAMPLE 4.5pF
INP INN
T/H
DEC
OUTPUT DRIVERS
REFOUT REFIN REFP COM REFN REFERENCE SYSTEM POWER CONTROL AND BIAS CIRCUITS
G/T
BOND WIRE INDUCTANCE 1.5nH INN
VDD
PD
CPAR 2pF
*CSAMPLE 4.5pF
Figure 2. Simplified Functional Diagram
SAMPLING CLOCK
Detailed Description
The MAX12555 uses a 10-stage, fully differential, pipelined architecture (Figure 1) that allows for highspeed conversion while minimizing power consumption. Samples taken at the inputs move progressively through the pipeline stages every half clock cycle. From input to output, the total clock-cycle latency is 8.0 clock cycles. Each pipeline converter stage converts its input voltage into a digital output code. At every stage, except the last, the error between the input voltage and the digital output code is multiplied and passed along to the next pipeline stage. Digital error correction compensates for ADC comparator offsets in each pipeline stage and ensures no missing codes. Figure 2 shows the MAX12555 functional diagram.
*THE EFFECTIVE RESISTANCE OF THE SWITCHED SAMPLING CAPACITORS IS: RSAMPLE = 1 fCLK x CSAMPLE
Figure 3. Simplified Input T/H Circuit
capacitors must be charged to one-half LSB accuracy within one-half of a clock cycle. The analog input of the MAX12555 supports differential or single-ended input drive. For optimum performance with differential inputs, balance the input impedance of INP and INN and set the common-mode voltage to midsupply (VDD / 2). The MAX12555 provides the optimum common-mode voltage of V DD / 2 through the COM output when operating in internal reference mode and buffered external reference mode. This COM output voltage can be used to bias the input network as shown in Figures 10, 11, and 12.
Input Track-and-Hold (T/H) Circuit
Figure 3 displays a simplified functional diagram of the input T/H circuit. This input T/H circuit allows for high analog input frequencies of 175MHz and beyond and supports a common-mode input voltage of VDD / 2 0.5V. The MAX12555 sampling clock controls the ADC's switched-capacitor T/H architecture (Figure 3) allowing the analog input signal to be stored as a charge on the sampling capacitors. These switches are closed (track) when the sampling clock is high and open (hold) when the sampling clock is low (Figure 4). The analog input signal source must be capable of providing the dynamic current necessary to charge and discharge the sampling capacitors. To avoid signal degradation, these
Reference Output (REFOUT)
An internal bandgap reference is the basis for all the internal voltages and bias currents used in the MAX12555. The power-down logic input (PD) enables and disables the reference circuit. The reference circuit requires 10ms to power up and settle when power is applied to the MAX12555 or when PD transitions from high to low. REFOUT has approximately 17k to GND when the MAX12555 is in power-down. The internal bandgap reference and its buffer generate VREFOUT to be 2.048V. The reference temperature coefficient is typically +50ppm/C. Connect an external 0.1F bypass capacitor from REFOUT to GND for stability.
14
______________________________________________________________________________________
14-Bit, 95Msps, 3.3V ADC MAX12555
CLKP CLKN tAD ANALOG INPUT tAJ SAMPLED DATA
T/H
TRACK
HOLD
TRACK
HOLD
TRACK
HOLD
TRACK
HOLD
Figure 4. T/H Aperture Timing
REFOUT sources up to 1.0mA and sinks up to 0.1mA for external circuits with a load regulation of 35mV/mA. Short-circuit protection limits I REFOUT to a 2.1mA source current when shorted to GND and a 0.24mA sink current when shorted to VDD.
resistive divider, use resistances 10k to avoid loading REFOUT. Buffered external reference mode is virtually identical to internal reference mode except that the reference source is derived from an external reference and not the MAX12555 REFOUT. In buffered external reference mode, apply a stable 0.7V to 2.2V source at REFIN. In this mode, COM, REFP, and REFN are low-impedance outputs with VCOM = VDD / 2, VREFP = VDD / 2 + VREFIN x 3/8, and VREFN = VDD / 2 - VREFIN x 3/8. To operate the MAX12555 in unbuffered external reference mode, connect REFIN to GND. Connecting REFIN to GND deactivates the on-chip reference buffers for COM, REFP, and REFN. With the respective buffers deactivated, COM, REFP, and REFN become highimpedance inputs and must be driven through separate, external reference sources. Drive VCOM to VDD / 2 5%, and drive REFP and REFN so VCOM = (VREFP + VREFN) / 2. The full-scale analog input range is (VREFP - VREFN) x 2/3.
Analog Inputs and Reference Configurations
The MAX12555 full-scale analog input range is adjustable from 0.35V to 1.10V with a VDD / 2 0.5V common-mode input range. The MAX12555 provides three modes of reference operation. The voltage at REFIN (V REFIN ) sets the reference operation mode (Table 1). To operate the MAX12555 with the internal reference, connect REFOUT to REFIN either with a direct short or through a resistive divider. In this mode, COM, REFP, and REFN are low-impedance outputs with V COM = VDD / 2, VREFP = VDD / 2 + VREFIN x 3/8, and VREFN = VDD / 2 - VREFIN x 3/8. The REFIN input impedance is very large (>50M). When driving REFIN through a
Table 1. Reference Modes
VREFIN REFERENCE MODE Internal Reference Mode. Drive REFIN with REFOUT either through a direct short or a resistive divider. The full-scale analog input range is VREFIN / 2: VCOM = VDD / 2 VREFP = VDD / 2 + VREFIN x 3/8 VREFN = VDD / 2 - VREFIN x 3/8 Buffered External Reference Mode. Apply an external 0.7V to 2.2V reference voltage to REFIN. The full-scale analog input range is VREFIN / 2: VCOM = VDD / 2 VREFP = VDD / 2 + VREFIN x 3/8 VREFN = VDD / 2 - VREFIN x 3/8 Unbuffered External Reference Mode. Drive REFP, REFN, and COM with external reference sources. The full-scale analog input range is (VREFP - VREFN) x 2/3.
35% VREFOUT to 100% VREFOUT
0.7V to 2.2V
<0.4V
______________________________________________________________________________________
15
14-Bit, 95Msps, 3.3V ADC
All three modes of reference operation require the same bypass capacitor combinations. Bypass COM with a 2.2F capacitor to GND. Bypass REFP and REFN each with a 0.1F capacitor to GND. Bypass REFP to REFN with a 1F capacitor in parallel with a 10F capacitor. Place the 1F capacitor as close to the device as possible on the same side of the PC board. Bypass REFIN and REFOUT to GND with a 0.1F capacitor. For detailed circuit suggestions, see Figure 13 and Figure 14.
MAX12555
VDD S1H
MAX12555
10k
CLKP 10k S2H S1L 10k CLKN 10k SWITCHES S1_ AND S2_ ARE OPEN DURING POWER-DOWN, MAKING CLKP AND CLKN HIGH IMPEDANCE. SWITCHES S2_ ARE OPEN IN SINGLE-ENDED CLOCK MODE. DUTY-CYCLE EQUALIZER
Clock Input and Clock Control Lines (CLKP, CLKN, CLKTYP)
The MAX12555 accepts both differential and singleended clock inputs. For single-ended clock input operation, connect CLKTYP to GND, CLKN to GND, and drive CLKP with the external single-ended clock signal. For differential clock input operation, connect CLKTYP to OVDD or VDD, and drive CLKP and CLKN with the external differential clock signal. To reduce clock jitter, the external single-ended clock must have sharp falling edges. Consider the clock input as an analog input and route it away from any other analog inputs and digital signal lines. CLKP and CLKN are high impedance when the MAX12555 is powered down (Figure 5). Low clock jitter is required for the specified SNR performance of the MAX12555. Analog input sampling occurs on the falling edge of the clock signal, requiring this edge to have the lowest possible jitter. Jitter limits the maximum SNR performance of any ADC according to the following relationship: 1 SNR = 20 x log 2 x fIN x t J where fIN represents the analog input frequency and tJ is the total system clock jitter. Clock jitter is especially critical for undersampling applications. For example, assuming that clock jitter is the only noise source, to obtain the specified 72.1dB of SNR with a 175MHz input frequency, the system must have less than 0.23ps of clock jitter. In actuality, there are other noise sources such as thermal noise and quantization noise that contribute to the system noise, requiring the clock jitter to be less than 0.14ps to obtain the specified 72.1dB of SNR at 175MHz.
S2L GND
Figure 5. Simplified Clock Input Circuit
Clock Duty-Cycle Equalizer (DCE)
Connect DCE high to enable the clock duty-cycle equalizer (DCE = OVDD or VDD). Connect DCE low to disable the clock duty-cycle equalizer (DCE = GND). With the clock duty-cycle equalizer enabled, the MAX12555 is insensitive to the duty cycle of the signal applied to CLKP and CLKN. Duty cycles from 35% to 65% are acceptable with the clock duty-cycle equalizer enabled. The clock duty-cycle equalizer uses a delay-locked loop (DLL) to create internal timing signals that are duty-cycle independent. Due to this DLL, the MAX12555 requires approximately 100 clock cycles to acquire and lock to new clock frequencies. Although not recommended, disabling the clock dutycycle equalizer reduces the analog supply current by 1.6mA. With the clock duty-cycle equalizer disabled, the MAX12555's dynamic performance varies depending on the duty cycle of the signal applied to CLKP and CLKN.
16
______________________________________________________________________________________
14-Bit, 95Msps, 3.3V ADC MAX12555
DIFFERENTIAL ANALOG INPUT (INP-INN) (VREFP - VREFN) x 2/3 N+3 N-3 N-2 N-1 N N+1 N +2
N+4
N+5 N+6 N+7 N+8 N+9
(VREFN - VREFP) x 2/3 tAD CLKN CLKP tDAV DAV tSETUP D0-D11 tHOLD N-3 8.0 CLOCK-CYCLE DATA LATENCY DOR N-2 tCL tCH
N-1
N
N+1
N+2
N+3
N+4
N+5 tSETUP
N+6
N+7
N+8
N+9 tHOLD
Figure 6. System Timing Diagram
System-Timing Requirements
Figure 6 shows the relationship between the clock, analog inputs, DAV indicator, DOR indicator, and the resulting output data. The analog input is sampled on the falling edge of the clock signal and the resulting data appears at the digital outputs 8.0 clock cycles later. The DAV indicator is synchronized with the digital output and optimized for use in latching data into digital back-end circuitry. Alternatively, digital back-end circuitry can be latched with the rising edge of the conversion clock (CLKP-CLKN). Data-Valid Output (DAV) DAV is a single-ended version of the input clock (CLKP) with a delay (tDAV). Output data changes on the falling edge of DAV, and DAV rises once output data is valid (Figure 6). The state of the duty-cycle equalizer input (DCE) changes the waveform at DAV. With the duty-cycle equalizer disabled (DCE = low), the DAV signal is a single-ended version of CLKP delayed by 5.2ns (tDAV).
With the duty-cycle equalizer enabled (DCE = high), the DAV signal has a fixed pulse width that is independent of CLKP. In either case, with DCE high or low, output data at D13-D0 and DOR are valid from 5.5ns before the rising edge of DAV to 4.0ns after the rising edge of DAV, and the falling edge of DAV is synchronized to have a 5.2ns (tDAV) delay from the falling edge of CLKP. DAV is high impedance when the MAX12555 is in power-down (PD = high). DAV is capable of sinking and sourcing 600A and has three times the drive strength of D13-D0 and DOR. DAV is typically used to latch the MAX12555 output data into an external backend digital circuit. Keep the capacitive load on DAV as low as possible (<25pF) to avoid large digital currents feeding back into the analog portion of the MAX12555 and degrading its dynamic performance. An external buffer on DAV isolates it from heavy capacitive loads. Refer to the MAX12555 evaluation kit schematic for an example of DAV driving back-end digital circuitry through an external buffer.
______________________________________________________________________________________
17
14-Bit, 95Msps, 3.3V ADC
Data Out-of-Range Indicator (DOR) The DOR digital output indicates when the analog input voltage is out of range. When DOR is high, the analog input is out of range. When DOR is low, the analog input is within range. The valid differential input range is from (VREFP - VREFN) x 3/4 to (VREFN - VREFP) x 3/4. Signals outside this valid differential range cause DOR to assert high as shown in Table 2 and Figure 6. DOR is synchronized with DAV and transitions along with the output data D13-D0. There is an 8.0 clockcycle latency in the DOR function as is with the output data (Figure 6). DOR is high impedance when the MAX12555 is in power-down (PD = high). DOR enters a high-impedance state within 10ns after the rising edge of PD and becomes active 10ns after PD's falling edge. Digital Output Data (D13-D0), Output Format (G/T) The MAX12555 provides a 14-bit, parallel, tri-state output bus. D13-D0 and DOR update on the falling edge of DAV and are valid on the rising edge of DAV. The MAX12555 output data format is either Gray code or two's complement, depending on the logic input G/T. With G/T high, the output data format is Gray code. With G/T low, the output data format is two's complement. See Figure 9 for a binary-to-Gray and Gray-tobinary code-conversion example. The following equations, Table 2, Figure 7, and Figure 8 define the relationship between the digital output and the analog input:
VINP - VINN = (VREFP - VREFN ) x 4 CODE10 - 8192 x 3 16384
MAX12555
VINP - VINN = (VREFP - VREFN ) x
4 CODE10 x 3 16384
for two's complement (G/T = 0). where CODE10 is the decimal equivalent of the digital output code as shown in Table 2. Digital outputs D13-D0 are high impedance when the MAX12555 is in power-down (PD = high). D13-D0 transition high 10ns after the rising edge of PD and become active 10ns after PD's falling edge. Keep the capacitive load on the MAX12555 digital outputs D13-D0 as low as possible (<15pF) to avoid large digital currents feeding back into the analog portion of the MAX12555 and degrading its dynamic performance. The addition of external digital buffers on the digital outputs isolates the MAX12555 from heavy capacitive loading. To improve the dynamic performance of the MAX12555, add 220 resistors in series with the digital outputs close to the MAX12555. Refer to the MAX12555 evaluation kit schematic for an example of the digital outputs driving a digital buffer through 220 series resistors.
Power-Down Input (PD)
The MAX12555 has two power modes that are controlled with the power-down digital input (PD). With PD low, the MAX12555 is in normal operating mode. With PD high, the MAX12555 is in power-down mode. The power-down mode allows the MAX12555 to efficiently use power by transitioning to a low-power state when conversions are not required. Additionally, the MAX12555 parallel output bus is high impedance in power-down mode, allowing other devices on the bus to be accessed.
for Gray code (G/T = 1).
18
______________________________________________________________________________________
Table 2. Output Codes vs. Input Voltage
TWO'S-COMPLEMENT OUTPUT CODE (G/T = 0)
GRAY-CODE OUTPUT CODE (G/T = 1)
(
>+1.023875V (DATA OUT OF RANGE) +1.023875V +1.023750V +0.000250V
VINP - VINN VREFP = 2.418V VREFN = 0.882V
)
BINARY D13 D0 DOR
DOR
DECIMAL HEXADECIMAL EQUIVALENT EQUIVALENT OF OF D13 D0 D13 D0 (CODE10) BINARY D13 D0
DECIMAL HEXADECIMAL EQUIVALENT EQUIVALENT OF OF D13 D0 D13 D0 (CODE10)
10 0000 0000 0000 1 0 0 0 0 0 0 0 0 0 1 0x0000 0 10 0000 0000 0000 1 0x0000 0 10 0000 0000 0000 0 0x0001 +1 10 0000 0000 0001 0 0x1001 +8190 11 1111 1111 1110 0 0x1000 +8191 11 1111 1111 1111 0 0x3FFF 0x3FFE 0x2001 0x2000 0x2000 0x3000 +8192 00 0000 0000 0000 0 0x0000 0x3001 +8193 00 0000 0000 0001 0 0x0001 0x3003 +8194 00 0000 0000 0010 0 0x0002 +2 +1 0 -1 -2 -8191 -8192 -8192 0x2001 +16382 01 1111 1111 1110 0 0x1FFE +8190 0x2000 +16383 01 1111 1111 1111 0 0x1FFF +8191 1
0x2000
+16383
01 1111 1111 1111
0x1FFF
+8191
10 0000 0000 0000
10 0000 0000 0001
11 0000 0000 0011
11 0000 0000 0001
+0.000125V +0.000000V -0.000125V -0.000250V -1.023875V -1.024000V <-1.024000V (DATA OUT OF RANGE)
11 0000 0000 0000
01 0000 0000 0000
01 0000 0000 0001
00 0000 0000 0001
00 0000 0000 0000
MAX12555
______________________________________________________________________________________
00 0000 0000 0000
14-Bit, 95Msps, 3.3V ADC
19
14-Bit, 95Msps, 3.3V ADC MAX12555
VREFP - VREFN 4 x 3 16384 (VREFP - VREFN) x 2/3 0x2000 0x2001 0x2003 GRAY OUTPUT CODE (LSB) VREFP - VREFN 4 x 3 16384 (VREFP - VREFN) x 2/3
1 LSB =
1 LSB =
(VREFP - VREFN) x 2/3 0x1FFF TWO'S-COMPLEMENT OUTPUT CODE (LSB) 0x1FFE 0x1FFD
(VREFP - VREFN) x 2/3
0x0001 0x0000 0x3FFF
0x3001 0x3000 0x1000
0x2003 0x2002 0x2001 0x2000 -8191 -8189 -1 0 +1 +8189 +8191
0x0002 0x0003 0x0001 0x0000 -8191 -8189 -1 0 +1 +8189 +8191
DIFFERENTIAL INPUT VOLTAGE (LSB)
DIFFERENTIAL INPUT VOLTAGE (LSB)
Figure 7. Two's-Complement Transfer Function (G/T = 0)
Figure 8. Gray-Code Transfer Function (G/T = 1)
In power-down mode, all internal circuits are off, the analog supply current reduces to 0.1mA, and the digital supply current reduces to 0.008mA. The following list shows the state of the analog inputs and digital outputs in power-down mode: * INP, INN analog inputs are disconnected from the internal input amplifier (Figure 3). * REFOUT has approximately 17k to GND. * REFP, COM, REFN go high impedance with respect to VDD and GND, but there is an internal 4k resistor between REFP and COM, as well as an internal 4k resistor between REFN and COM. * D13-D0, DOR, and DAV go high impedance. * CLKP, CLKN go high impedance (Figure 5). The wake-up time from power-down mode is dominated by the time required to charge the capacitors at REFP, REFN, and COM. In internal reference mode and buffered external reference mode, the wake-up time is typically 10ms with the recommended capacitor array (Figure 13). When operating in unbuffered external reference mode, the wake-up time is dependent on the external reference drivers.
Applications Information
Using Transformer Coupling
In general, the MAX12555 provides better SFDR and THD performance with fully differential input signals as opposed to single-ended input drive. In differential input mode, even-order harmonics are lower as both inputs are balanced, and each of the ADC inputs only requires half the signal swing compared to singleended input mode. An RF transformer (Figure 10) provides an excellent solution to convert a single-ended input source signal to a fully differential signal, required by the MAX12555 for optimum performance. Connecting the center tap of the transformer to COM provides a VDD / 2 DC level shift to the input. Although a 1:1 transformer is shown, a step-up transformer can be selected to reduce the drive requirements. A reduced signal swing from the input driver, such as an op amp, can also improve the overall distortion. The configuration of Figure 10 is good for frequencies up to Nyquist (fCLK / 2). The circuit of Figure 11 converts a single-ended input signal to fully differential just as Figure 10. However, Figure 11 utilizes an additional transformer to improve the common-mode rejection, allowing high-frequency
20
______________________________________________________________________________________
14-Bit, 95Msps, 3.3V ADC MAX12555
BINARY-TO-GRAY-CODE CONVERSION 1) THE MOST SIGNIFICANT GRAY-CODE BIT IS THE SAME AS THE MOST SIGNIFICANT BINARY BIT. D13 01 0 2) SUBSEQUENT GRAY-CODE BITS ARE FOUND ACCORDING TO THE FOLLOWING EQUATION: GRAYX = BINARYX BINARYX+1 WHERE IS THE EXCLUSIVE OR FUNCTION (SEE TRUTH TABLE BELOW) AND X IS THE BIT POSITION. GRAY12 = BINARY12 GRAY12 = 1 0 GRAY12 = 1 D13 0 0 1 1 D11 1011 D7 0100 D3 D0 BIT POSITION BINARY GRAY CODE BINARY13 D11 1011 D7 0100 D3 D0 1100 BIT POSITION BINARY GRAY CODE GRAY-TO-BINARY-CODE CONVERSION 1) THE MOST SIGNIFICANT BINARY BIT IS THE SAME AS THE MOST SIGNIFICANT GRAY-CODE BIT. D13 01 0 2) SUBSEQUENT BINARY BITS ARE FOUND ACCORDING TO THE FOLLOWING EQUATION: BINARYX = BINARYX+1 GRAYX WHERE IS THE EXCLUSIVE OR FUNCTION (SEE TRUTH TABLE BELOW) AND X IS THE BIT POSITION. BINARY12 = BINARY13 BINARY12 = 0 1 BINARY12 = 1 D13 0 0 1 1 D11 0110 D7 1110 D3 D0 BIT POSITION GRAY CODE BINARY GRAY12 D11 0110 D7 1110 D3 D0 1010 BIT POSITION GRAY CODE BINARY
1100
1010
3) REPEAT STEP 2 UNTIL COMPLETE. GRAY11 = BINARY11 GRAY11 = 1 1 GRAY11 = 0 D13 01 01 D11 1011 0 D7 0100 D3 D0 BIT POSITION BINARY GRAY CODE BINARY12
3) REPEAT STEP 2 UNTIL COMPLETE. BINARY11 = BINARY12 BINARY11 = 1 0 BINARY11 = 1 D13 01 01 D11 0110 1 D7 1110 D3 D0 BIT POSITION GRAY CODE BINARY GRAY11
1100
1010
4) THE FINAL GRAY-CODE CONVERSION IS: D13 01 01 D11 1011 0110 D7 0100 1110 D3 D0 BIT POSITION BINARY GRAY CODE
4) THE FINAL GRAY-CODE CONVERSION IS: D13 01 01 D11 0110 1011 D7 1110 0100 D3 D0 BIT POSITION GRAY CODE BINARY
1100 1010
1010 1100
EXCULSIVE OR TRUTH TABLE A 0 0 1 1 B 0 1 0 1 Y=A 0 1 1 0 B
Figure 9. Binary-to-Gray and Gray-to-Binary Code Conversion
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21
14-Bit, 95Msps, 3.3V ADC MAX12555
MAX4108 24.9 0.1F VIN N.C. 1 T1 2 5 2.2F 3 4 MINI-CIRCUITS TT1-6 OR T1-1T 24.9 INN 12pF 5.6pF 100 24.9 INN COM 2.2F 6 12pF INP VIN 0.1F INP 5.6pF 100 24.9 COM
MAX12555
MAX12555
Figure 10. Transformer-Coupled Input Drive for Input Frequencies Up to Nyquist
Figure 12. Single-Ended, AC-Coupled Input Drive
0* 0.1F VIN N.C. 1 T1 2 5 75 0.5% 6 75 0.5% N.C. 1 T2 2 5 N.C. 110 0.1% 2.2F 0* INN 5.6pF *0 RESISTORS CAN BE REPLACED WITH LOW-VALUE RESISTORS TO LIMIT THE BANDWIDTH. 6 110 0.1% 5.6pF INP
MAX12555
COM
3 4 MINI-CIRCUITS ADT1-1WT
3 4 MINI-CIRCUITS ADT1-1WT
Figure 11. Transformer-Coupled Input Drive for Input Frequencies Beyond Nyquist
signals beyond the Nyquist frequency. The two sets of termination resistors provide an equivalent 50 termination to the signal source. The second set of termination resistors connects to COM, providing the correct input common-mode voltage. Two 0 resistors in series with the analog inputs allow high IF input frequencies. These 0 resistors can be replaced with low-value resistors to limit the input bandwidth.
Single-Ended, AC-Coupled Input Signal
Figure 12 shows an AC-coupled, single-ended input application. The MAX4108 provides high speed, high bandwidth, low noise, and low distortion to maintain the input signal integrity.
22
______________________________________________________________________________________
14-Bit, 95Msps, 3.3V ADC MAX12555
+3.3V 2.2F 0.1F +3.3V 1 2 0.1F
MAX6029EUK21
0.1F 5 2.048V NOTE: ONE FRONT-END REFERENCE CIRCUIT IS CAPABLE OF SOURCING 15mA AND SINKING 30mA OF OUTPUT CURRENT. 0.1F 16.2k 1 1F 3 2 5 +3.3V 0.1F
VDD 38 REFOUT
REFP
1
1F*
10F
MAX12555
REFN 2
0.1F 3 REFIN GND COM 2.2F
39
MAX4230
4 47
2.048V
+3.3V 10F 6V 330F 6V 2.2F 0.1F 0.1F
1.47k VDD *PLACE THE 1F REFP-to-REFN BYPASS CAPACITOR AS CLOSE TO THE DEVICE AS POSSIBLE. 0.1F 38 REFOUT 1F* 10F REFP 1
MAX12555
REFN 2
0.1F 3 REFIN GND COM 2.2F
39
Figure 13. External Buffered Reference Driving Multiple ADCs
Buffered External Reference Drives Multiple ADCs
The buffered external reference mode allows for more control over the MAX12555 reference voltage and allows multiple converters to use a common reference. The REFIN input impedance is >50M.
Figure 13 uses the MAX6029EUK21 precision 2.048V reference as a common reference for multiple converters. The 2.048V output of the MAX6029 passes through a one-pole 10Hz lowpass filter to the MAX4230. The MAX4230 buffers the 2.048V reference and provides additional 10Hz lowpass filtering before its output is applied to the REFIN input of the MAX12555.
______________________________________________________________________________________
23
14-Bit, 95Msps, 3.3V ADC MAX12555
+3.3V 1 0.1F 2
MAX6029EUK30
+3.3V 5 3.000V 0.1F 1 20k 1% 3 20k 1% 2 5 0.1F +3.3V 0.1F 2.2F
MAX4230
4 47
2.413V 1 330F 6V REFP VDD REFOUT 38 0.1F 2
10F 6V 1.47k
10F
1F*
MAX12555
REFN
0.47F 52.3k 1%
0.1F
+3.3V
0.1F
1 52.3k 1%
5
MAX4230
4 47
3 1.647V 2.2F
COM
GND
REFIN
39
3
2
10F 6V
330F 6V 0.1F
+3.3V 2.2F 0.1F
20k 1% 20k 1% 20k 1% 0.1F +3.3V
1.47k 1 1 VDD REFOUT 0.880V 47 10F 1F* 38 0.1F
REFP
5
MAX4230
4
MAX12555
2 330F 6V REFN
3
2
10F 6V
0.1F
1.47k *PLACE THE 1F REFP-TO-REFN BYPASS CAPACITOR AS CLOSE TO THE DEVICE AS POSSIBLE. 2.2F
3
COM
GND
REFIN
39
Figure 14. External Unbuffered Reference Driving Multiple ADCs
Unbuffered External Reference Drives Multiple ADCs
The unbuffered external reference mode allows for precise control over the MAX12555 reference and allows multiple converters to use a common reference. Connecting REFIN to GND disables the internal reference, allowing REFP, REFN, and COM to be driven directly by a set of external reference sources.
24
Figure 14 uses the MAX6029EUK30 precision 3.000V reference as a common reference for multiple converters. A seven-component resistive divider chain follows the MAX6029 voltage reference. The 0.47F capacitor along this chain creates a 10Hz lowpass filter. Three MAX4230 operational amplifiers buffer taps along this resistor chain providing 2.413V, 1.647V, and 0.880V to the MAX12555's REFP, COM, REFN reference inputs,
______________________________________________________________________________________
14-Bit, 95Msps, 3.3V ADC
respectively. The feedback around the MAX4230 op amps provides additional 10Hz lowpass filtering. The 2.413V and 0.880V reference voltages set the full-scale analog input range to 1.022V = (VREFP - VREFN) x 2/3. A common power source for all active components removes any concern regarding power-supply sequencing when powering up or down. missing codes and a monotonic transfer function. For the MAX12555, DNL deviations are measured at every step of the transfer function and the worst-case deviation is reported in the Electrical Characteristics table.
MAX12555
Offset Error
Offset error is a figure of merit that indicates how well the actual transfer function matches the ideal transfer function at a single point. Ideally the midscale MAX12555 transition occurs at 0.5 LSB above midscale. The offset error is the amount of deviation between the measured midscale transition point and the ideal midscale transition point.
Grounding, Bypassing, and Board Layout
The MAX12555 requires high-speed board layout design techniques. Refer to the MAX12555 evaluation kit data sheet for a board layout reference. Locate all bypass capacitors as close to the device as possible, preferably on the same side of the board as the ADC, using surface-mount devices for minimum inductance. Bypass VDD to GND with a 0.1F ceramic capacitor in parallel with a 2.2F ceramic capacitor. Bypass OVDD to GND with a 0.1F ceramic capacitor in parallel with a 2.2F ceramic capacitor. Multilayer boards with ample ground and power planes produce the highest level of signal integrity. All MAX12555 GNDs and the exposed back-side paddle must be connected to the same ground plane. The MAX12555 relies on the exposed back-side paddle connection for a low-inductance ground connection. Use multiple vias to connect the top-side ground to the bottom-side ground. Isolate the ground plane from any noisy digital system ground planes such as a DSP or output buffer ground. Route high-speed digital signal traces away from the sensitive analog traces. Keep all signal lines short and free of 90 turns. Ensure that the differential analog input network layout is symmetric and that all parasitics are balanced equally. Refer to the MAX12555 evaluation kit data sheet for an example of symmetric input layout.
Gain Error
Gain error is a figure of merit that indicates how well the slope of the actual transfer function matches the slope of the ideal transfer function. The slope of the actual transfer function is measured between two data points: positive full scale and negative full scale. Ideally, the positive full-scale MAX12555 transition occurs at 1.5 LSBs below positive full scale, and the negative fullscale transition occurs at 0.5 LSB above negative full scale. The gain error is the difference of the measured transition points minus the difference of the ideal transition points.
Small-Signal Noise Floor (SSNF)
Small-signal noise floor is the integrated noise and distortion power in the Nyquist band for small-signal inputs. The DC offset is excluded from this noise calculation. For this converter, a small signal is defined as a single tone with an amplitude less than -35dBFS. This parameter captures the thermal and quantization noise characteristics of the converter and is used to help calculate the overall noise figure of a receive channel. Go to www.maxim-ic.com for application notes on thermal + quantization noise floor.
Parameter Definitions
Integral Nonlinearity (INL)
Integral nonlinearity is the deviation of the values on an actual transfer function from a straight line. For the MAX12555, this straight line is between the end points of the transfer function, once offset and gain errors have been nullified. INL deviations are measured at every step of the transfer function and the worst-case deviation is reported in the Electrical Characteristics table.
Signal-to-Noise Ratio (SNR)
For a waveform perfectly reconstructed from digital samples, the theoretical maximum SNR is the ratio of the full-scale analog input (RMS value) to the RMS quantization error (residual error). The ideal, theoretical minimum analog-to-digital noise is caused by quantization error only and results directly from the ADC's resolution (N bits): SNR[max] = 6.02 x N + 1.76 In reality, there are other noise sources besides quantization noise: thermal noise, reference noise, clock jitter, etc. SNR is computed by taking the ratio of the RMS signal to the RMS noise. RMS noise includes all spectral components to the Nyquist frequency excluding the
Differential Nonlinearity (DNL)
Differential nonlinearity is the difference between an actual step width and the ideal value of 1 LSB. A DNL error specification of less than 1 LSB guarantees no
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25
14-Bit, 95Msps, 3.3V ADC MAX12555
fundamental, the first six harmonics (HD2-HD7), and the DC offset:
Intermodulation Distortion (IMD)
IMD is the ratio of the RMS sum of the intermodulation products to the RMS sum of the two fundamental input tones. This is expressed as:
VIM12 + VIM22 + ....... + VIM132 + VIM14 2 IMD = 20 x log V12 + V22
SIGNALRMS SNR = 20 x log NOISERMS
Signal-to-Noise Plus Distortion (SINAD)
SINAD is computed by taking the ratio of the RMS signal to the RMS noise plus the RMS distortion. RMS noise includes all spectral components to the Nyquist frequency excluding the fundamental, the first six harmonics (HD2-HD7), and the DC offset. RMS distortion includes the first six harmonics (HD2-HD7):
SIGNALRMS SINAD = 20 x log 2 2 NOISERMS + DISTORTIONRMS
The fundamental input tone amplitudes (V1 and V2) are at -7dBFS. Fourteen intermodulation products (VIM_) are used in the MAX12555 IMD calculation. The intermodulation products are the amplitudes of the output spectrum at the following frequencies, where fIN1 and fIN2 are the fundamental input tone frequencies: * Second-order intermodulation products: fIN1 + fIN2, fIN2 - fIN1 * Third-order intermodulation products: 2 x fIN1 - fIN2, 2 x fIN2 - fIN1, 2 x fIN1 + fIN2, 2 x fIN2 + fIN1 * Fourth-order intermodulation products: 3 x fIN1 - fIN2, 3 x fIN2 - fIN1, 3 x fIN1 + fIN2, 3 x fIN2 + fIN1 * Fifth-order intermodulation products: 3 x fIN1 - 2 x fIN2, 3 x fIN2 - 2 x fIN1, 3 x fIN1 + 2 x fIN2, 3 x fIN2 + 2 x fIN1
Effective Number of Bits (ENOB)
ENOB specifies the dynamic performance of an ADC at a specific input frequency and sampling rate. An ideal ADC's error consists of quantization noise only. ENOB for a full-scale sinusoidal input waveform is computed from: SINAD - 1.76 ENOB = 6.02
Third-Order Intermodulation (IM3)
IM3 is the total power of the third-order intermodulation products to the Nyquist frequency relative to the total input power of the two input tones fIN1 and fIN2. The individual input tone levels are at -7dBFS. The thirdorder intermodulation products are 2 x fIN1 - fIN2, 2 x fIN2 - fIN1, 2 x fIN1 + fIN2, 2 x fIN2 + fIN1.
Single-Tone Spurious-Free Dynamic Range (SFDR)
SFDR is the ratio expressed in decibels of the RMS amplitude of the fundamental (maximum signal component) to the RMS amplitude of the next-largest spurious component, excluding DC offset.
Two-Tone Spurious-Free Dynamic Range (SFDRTT)
SFDRTT represents the ratio, expressed in decibels, of the RMS amplitude of either input tone to the RMS amplitude of the next-largest spurious component in the spectrum, excluding DC offset. This spurious component can occur anywhere in the spectrum up to Nyquist and is usually an intermodulation product or a harmonic.
Total Harmonic Distortion (THD)
THD is the ratio of the RMS sum of the first six harmonics of the input signal to the fundamental itself. This is expressed as:
2 2 2 2 2 2 V2 + V3 + V4 + V5 + V6 + V7 THD = 20 x log V1
Aperture Delay
The MAX12555 samples data on the falling edge of its sampling clock. In actuality, there is a small delay between the falling edge of the sampling clock and the actual sampling instant. Aperture delay (tAD) is the time defined between the falling edge of the sampling clock and the instant when an actual sample is taken (Figure 4).
where V1 is the fundamental amplitude, and V2 through V7 are the amplitudes of the 2nd- through 7th-order harmonics (HD2-HD7).
26
______________________________________________________________________________________
14-Bit, 95Msps, 3.3V ADC
Aperture Jitter
REFOUT
MAX12555
Figure 4 depicts the aperture jitter (tAJ), which is the sample-to-sample variation in the aperture delay.
G/T
Pin Configuration
OVDD GND DAV VDD TOP VIEW REFIN PD
D0
The output noise (nOUT) parameter is similar to the thermal + quantization noise parameter and is an indication of the ADC's overall noise performance. No fundamental input tone is used to test for nOUT; INP, INN, and COM are connected together and 1024k data points collected. nOUT is computed by taking the RMS value of the collected data points after the mean is removed.
40 39 38 37 36 35 34 33 32 31 REFP REFN COM GND INP INN GND DCE CLKN CLKP 1 2 3 4 5 6 7 8 9 10 EXPOSED PADDLE (GND) 11 12 13 14 15 16 17 18 19 20 CLKTYP D13 GND OVDD DOR D12 VDD VDD VDD VDD 30 29 28 27 26 25 24 23 22 21 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11
MAX12555
Overdrive Recovery Time
Overdrive recovery time is the time required for the ADC to recover from an input transient that exceeds the full-scale limits. The MAX12555 specifies overdrive recovery time using an input transient that exceeds the full-scale limits by 10%.
THIN QFN 6mm x 6mm x 0.8mm
______________________________________________________________________________________
D1
Output Noise (nOUT)
27
14-Bit, 95Msps, 3.3V ADC MAX12555
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
QFN THIN 6x6x0.8.EPS
E2 L e
D2 D D/2 k
C L
b D2/2
E/2 E2/2 E (NE-1) X e
C L
k
e (ND-1) X e
L
e L
C L C L
L1 L
e
A1
A2
A
PACKAGE OUTLINE 36, 40, 48L THIN QFN, 6x6x0.8mm
21-0141
E
1 2
NOTES: 1. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994. 2. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES. 3. N IS THE TOTAL NUMBER OF TERMINALS. 4. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JESD 95-1 SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE. 5. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.25 mm AND 0.30 mm FROM TERMINAL TIP. 6. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY. 7. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION. 8. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS. 9. DRAWING CONFORMS TO JEDEC MO220, EXCEPT FOR 0.4mm LEAD PITCH PACKAGE T4866-1. 10. WARPAGE SHALL NOT EXCEED 0.10 mm.
PACKAGE OUTLINE 36, 40, 48L THIN QFN, 6x6x0.8mm
21-0141
E
2 2
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
28 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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