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19-1552; Rev 0; 10/99
Ultra-Low-Distortion, Single-Supply, 300MHz Op Amps with Enable
General Description
The MAX4265-MAX4270 single-supply, voltage-feedback op amps are capable of driving a 100 load while maintaining ultra-low distortion over a wide bandwidth. They offer superior spurious-free dynamic range (SFDR) performance: -90dBc or better at frequencies below 5MHz and -60dBc at a 100MHz frequency. Additionally, input voltage noise density is 8nV/Hz while operating from a single +4.5V to +8.0V supply or from dual 2.25V to 4.0V supplies. These features make the MAX4265-MAX4270 ideal for use in high-performance communications and signalprocessing applications that require low distortion and wide bandwidth. The MAX4265 single and MAX4268 dual unity-gain-stable amplifiers have up to a 300MHz gain-bandwidth product. The MAX4266 single and MAX4269 dual amplifiers have up to a 350MHz bandwidth at a minimum stable gain of +2V/V. The MAX4267 single and MAX4270 dual amplifiers have a 200MHz bandwidth at a minimum stable gain of +5V/V. For additional power savings, these amplifiers feature a low-power disable mode that reduces supply current to 1.6mA and places the outputs in a high-impedance state. The MAX4265/MAX4266/MAX4267 are available in a space-saving 8-pin MAX package, and the MAX4268/ MAX4269/MAX4270 are available in a 16-pin QSOP package. o Superior SFDR with 100 Load -90dBc (fC = 5MHz ) -60dBc (fC = 100MHz) o 35dBm IP3 (fC = 20MHz) o 8nV/Hz Voltage Noise Density o 100MHz 0.1dB Gain Flatness (MAX4268) o 900V/s Slew Rate o 45mA Output Driving Capability o Shutdown Mode Places Outputs in HighImpedance State
Features
o +4.5V to +8.0V Single-Supply Operation
MAX4265-MAX4270
Ordering Information
PART MAX4265EUA* MAX4265ESA* MAX4266EUA* MAX4266ESA* MAX4267EUA* MAX4267ESA* MAX4268EEE MAX4268ESD MAX4269EEE MAX4269ESD MAX4270EEE MAX4270ESD TEMP. RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 8 MAX 8 SO 8 MAX 8 SO 8 MAX 8 SO 16 QSOP 14 SO 16 QSOP 14 SO 16 QSOP 14 SO
Applications
Base-Station Amplifiers IF Amplifiers High-Frequency ADC Drivers High-Speed DAC Buffers RF Telecom Applications High-Frequency Signal Processing
Pin Configurations appear at end of data sheet.
*Future product--contact factory for availability.
SFDR vs. Input Frequency
VOUT = 1Vp-p RL = 100 to VCC/2
MAX4268/70 toc10
-20 -30 -40 SFDR (dBc) -50 -60 -70 -80 -90 -100 0.1M 1M 10M MAX4269 MAX4270
Selector Guide
PART MAX4265 MAX4266 MAX4267 MAX4268 MAX4269 MAX4270 NO. OF OP AMPS 1 1 1 2 2 2 MIN GAIN (V/V) 1 2 5 1 2 5 BANDWIDTH (MHz) 300 350 200 300 350 200
MAX4268 100M
FREQUENCY (Hz)
________________________________________________________________ Maxim Integrated Products
1
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Ultra-Low-Distortion, Single-Supply, 300MHz Op Amps with Enable MAX4265-MAX4270
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (VCC to VEE)...............................................+8.5V Voltage on Any Other Pin .................(VEE - 0.3V) to (VCC + 0.3V) Short-Circuit Duration (VOUT to VCC or VEE) ..............Continuous Continuous Power Dissipation (TA = +70C) 16-Pin QSOP (derate 8.33mW/C above +70C)........667mW 8-Pin MAX (derate 4.10mW/C above +70C) ..........330mW 8-Pin SO (derate 5.9mW/C above +70C).................471mW 14-Pin SO (derate 8.33mW/C above +70C).............667mW Operating Temperature Range ...........................-40C to +85C Storage Temperature Range .............................-65C to +150C Junction Temperature ......................................................+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.
DC ELECTRICAL CHARACTERISTICS
(VCC = +5V, VEE = 0, RL = 100 to VCC/2, VCM = VCC/2, TA = TMIN to TMAX, typical values are at TA = +25C, unless otherwise noted.) PARAMETER Operating Supply Voltage Range Common-Mode Input Voltage Input Offset Voltage Input Offset Voltage Drift Input Offset Voltage Channel Matching Input Bias Current Input Offset Current Common-Mode Input Resistance Differential Input Resistance Common-Mode Rejection Ratio Power-Supply Rejection Ratio Open-Loop Voltage Gain Output Voltage Swing Output Current Drive Output Short-Circuit Current Closed-Loop Output Resistance Power-Up Time Quiescent Supply Current Disable Output Leakage Current EN_ Logic Low Threshold EN_ Logic High Threshold EN_ Logic Input Low Current EN_ Logic Input High Current VEN_ = 0 VEN_ = 5V VCC - 1.5 5 1 100 30 IB IOS RINCM RINDIFF CMRR PSRR AOL VOUT IOUT ISC ROUT tPWRUP IS VO = 1V step, 0.1% settling time Normal mode, EN_ = 5V or floating Disable mode, EN_ = 0 VEN_ = 0, VEE VOUT VCC Either input, (VEE + 1.6) VCM (VCC - 1.6) -10mV VIN 10mV (VEE + 1.6V) VCM (VCC - 1.6V), no load VCC = 4.5V to 8.0V 1.75V VOUT 3.25V VCC - VOH, VOL - VEE RL = 20 Sinking or sourcing to VCC or VEE 30 60 60 60 SYMBOL VCC VCM VOS TCVOS MAX4268/MAX4269/MAX4270 CONDITIONS Inferred from PSRR test Inferred from CMRR test MIN 4.5 VEE + 1.6 1 1.5 1 3.5 0.1 1 40 85 85 95 1.1 45 100 0.035 10 28 1.6 0.2 32 5 5 VCC - 3.5 1.5 40 5.5 TYP MAX 8.0 VCC - 1.6 9 UNITS V V mV V/C mV A A M k dB dB dB dB mA mA s mA A V V A A
2
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Ultra-Low-Distortion, Single-Supply, 300MHz Op Amps with Enable
AC ELECTRICAL CHARACTERISTICS
(VCC = +5V, VEE = 0, RL = 100 to VCC/2, VCM = VCC/2, MAX4265/MAX4268 AV = +1V/V, MAX4266/MAX4269 AV = +2V/V, MAX4267/MAX4270 AV = +5V/V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Small-Signal -3dB Bandwidth SYMBOL BW-3dB CONDITIONS MAX4265/MAX4268 VOUT = 100mVp-p MAX4266/MAX4269 MAX4267/MAX4270 MAX4265/MAX4268 Full-Power Bandwidth FPBW VOUT = 1Vp-p MAX4266/MAX4269 MAX4267/MAX4270 MAX4265/MAX4268 0.1dB Gain Flatness All-Hostile Crosstalk Slew Rate Rise/Fall Times Settling Time (0.1%) SR tR, tF tS,0.1 BW0.1dB VOUT = 100mVp-p f = 10MHz VOUT = 1V step VOUT = 1V step VOUT = 1V step VOUT = 1V step fC = 1MHz fC = 5MHz Spurious-Free Dynamic Range SFDR VOUT = 1Vp-p (MAX4269) fC = 10MHz fC = 20MHz fC = 60MHz fC = 100MHz fC = 1MHz fC = 5MHz Second Harmonic Distortion VOUT = 1Vp-p (MAX4269) fC = 10MHz fC = 20MHz fC = 60MHz fC = 100MHz fC = 1MHz fC = 5MHz Third Harmonic Distortion VOUT = 1Vp-p (MAX4269) fC = 10MHz fC = 20MHz fC = 60MHz fC = 100MHz MAX4266/MAX4269 MAX4267/MAX4270 MIN TYP 300 350 200 175 200 200 100 35 35 85 900 1 15 88 90 87 78 68 60 88 90 87 78 68 60 96 95 92 86 72 68 dBc dBc dBc dB V/s ns ns MHz MHz MHz MAX UNITS
MAX4265-MAX4270
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Ultra-Low-Distortion, Single-Supply, 300MHz Op Amps with Enable MAX4265-MAX4270
AC ELECTRICAL CHARACTERISTICS (continued)
(VCC = +5V, VEE = 0, RL = 100 to VCC/2, VCM = VCC/2, MAX4265/MAX4268 AV = +1V/V, MAX4266/MAX4269 AV = +2V/V, MAX4267/MAX4270 AV = +5V/V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Two-Tone, Third-Order Intercept Distortion Input -1dB Compression Point Differential Gain Differential Phase Input Capacitance Output Impedance Disabled Output Capacitance Enable Time Disable Time Capacitive Load Stability Input Voltage Noise Density Input Current Noise Density en in tEN tDIS DG DP CIN ROUT f = 10MHz VEN_ = 0 VIN = 1V VIN = 1V MAX4265/MAX4268 No sustained oscillation f = 1kHz f = 1kHz MAX4266/MAX4269 MAX4267/MAX4270 SYMBOL IP3 CONDITIONS VOUT = 1Vp-p, fCA = 20MHz, fCB = 21.25MHz (MAX4269) fC = 20MHz NTSC, f = 3.58MHz, RL = 150 to VCC/2 NTSC, f = 3.58MHz, RL = 150 to VCC/2 MIN TYP 35 12 0.015 0.03 2 1 5 100 750 15 15 22 8 1 nV/Hz pA/Hz pF MAX UNITS dBm dBm % degrees pF pF ns s
Typical Operating Characteristics
(VCC = +5V, VEE = 0, EN_ = 5V, RL = 100 to VCC/2, MAX4268 AV = +1V/V, MAX4269 AV = +2V/V, MAX4270 AV = +5V/V, TA =+25C, unless otherwise noted.)
SMALL-SIGNAL BANDWIDTH
MAX4268/70 toc01a
LARGE-SIGNAL GAIN vs. FREQUENCY
3 2 1 GAIN (dB) 0 -1 -2 -3 MAX4269 MAX4270 MAX4268 GAIN (dB) VOUT = 1Vp-p
MAX4268/70 toc02a
GAIN FLATNESS vs. FREQUENCY
0.3 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 -0.5 -0.6 MAX4270 MAX4269 MAX4268
MAX4268/70 toc3
4 3 2 1 GAIN (dB) 0 -1 -2 -3 -4 -5 -6
VOUT = 100mVp-p
4
0.4
MAX4268
MAX4269
MAX4270
-4 -5 -6
0.1M
1M
10M FREQUENCY (Hz)
100M
1G
0.1M
1M
10M FREQUENCY (Hz)
100M
1G
0.1M
1M
10M FREQUENCY (Hz)
100M
1G
4
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Ultra-Low-Distortion, Single-Supply, 300MHz Op Amps with Enable
Typical Operating Characteristics (continued)
(VCC = +5V, VEE = 0, EN_ = 5V, RL = 100 to VCC/2, MAX4268 AV = +1V/V, MAX4269 AV = +2V/V, MAX4270 AV = +5V/V, TA =+25C, unless otherwise noted.)
MAX4268 DISTORTION vs. FREQUENCY
MAX4268/70 toc04
MAX4265-MAX4270
MAX4269 DISTORTION vs. FREQUENCY
VOUT = 1Vp-p -30 -40 DISTORTION (dBc) -50 -60 -70 -80 -90 -100 2ND HARMONIC 3RD HARMONIC
MAX4268/70 toc05
MAX4270 DISTORTION vs. FREQUENCY
VOUT = 1Vp-p -30 -40 DISTORTION (dBc) -50 -60 -70 -80 -90 2ND HARMONIC 3RD HARMONIC 1M 10M 100M
MAX4268/70 toc06
-20 VOUT = 1Vp-p -30 -40 DISTORTION (dBc) -50 -60 -70 -80 -90 -100 0.1M 1M 10M 2ND HARMONIC 3RD HARMONIC
-20
-20
100M
0.1M
1M
10M
100M
-100 0.1M
FREQUENCY (Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
MAX4268 DISTORTION vs. LOAD
MAX4268/70 toc07
MAX4269 DISTORTION vs. LOAD
MAX4268/70 toc08
MAX4270 DISTORTION vs. LOAD
-30 -40 DISTORTION (dBc) -50 -60 -70 -80 -90 -100 600 0 100 2ND HARMONIC 3RD HARMONIC 200 300 400 500 600 fO = 5MHz VOUT = 1Vp-p
MAX4268/70 toc09
-20 -30 -40 DISTORTION (dBc) -50 -60 -70 -80 -90 -100 0 100 200 300 400 500 2ND HARMONIC 3RD HARMONIC fO = 5MHz VOUT = 1Vp-p
-20 -30 -40 DISTORTION (dBc) -50 -60 -70 -80 -90 -100 2ND HARMONIC 3RD HARMONIC 0 100 200 300 400 500 fO = 5MHz VOUT = 1Vp-p
-20
600
RESISTIVE LOAD ()
RESISTIVE LOAD ()
RESISTIVE LOAD ()
MAX4268 DISTORTION vs. VOLTAGE SWING
MAX4268/70 toc10
MAX4269 DISTORTION vs. VOLTAGE SWING
MAX4268/70 toc11
MAX4270 DISTORTION vs. VOLTAGE SWING
fO = 5MHz -30 -40 DISTORTION (dBc) -50 -60 -70 -80 -90 -100 2ND HARMONIC 3RD HARMONIC 0 0.5 1.0 1.5 2.0 2.5
MAX4268/70 toc12
-20 -30 -40 DISTORTION (dBc) -50 -60 -70
fO = 5MHz
-20 -30 -40 DISTORTION (dBc) -50 -60 -70 -80
-20
fO = 5MHz
2ND HARMONIC -80 -90 3RD HARMONIC -100 0 0.5 1.0 1.5 2.0 2.5 VOLTAGE SWING (Vp-p)
2ND HARMONIC 3RD HARMONIC
-90 -100 0 0.5 1.0 1.5 2.0 2.5 VOLTAGE SWING (Vp-p)
VOLTAGE SWING (Vp-p)
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Ultra-Low-Distortion, Single-Supply, 300MHz Op Amps with Enable MAX4265-MAX4270
Typical Operating Characteristics (continued)
(VCC = +5V, VEE = 0, EN_ = 5V, RL = 100 to VCC/2, MAX4268 AV = +1V/V, MAX4269 AV = +2V/V, MAX4270 AV = +5V/V, TA =+25C, unless otherwise noted.)
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4268/70 toc13
SPURIOUS-FREE DYNAMIC RANGE vs. FREQUENCY
VOUT = 1Vp-p -30 -40 SFDR (dBc) -50 -60 -70 MAX4270 MAX4269
MAX4268/70 toc14
TWO-TONE THIRD-ORDER INTERCEPT vs. FREQUENCY
55 50 INTERCEPT (dBm) 45 40 35 30 MAX4270 MAX4268 MAX4269
MAX4268/70 toc15
0.1 VOUT = 1Vp-p
-20
60
THD + NOISE (%)
MAX4270 0.01
MAX4269 0.001 0.1M
MAX4268
-80 -90 -100
MAX4268 0.1M 1M 10M 100M
25 20 0.1M 1M 10M 100M
1M
10M
100M
FREQUENCY (Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
VOLTAGE NOISE vs. FREQUENCY
MAX4268/70 toc16
OUTPUT IMPEDANCE vs. FREQUENCY
MAX4268/70 toc17
MAX4268/MAX4269/MAX4290 CROSSTALK vs. FREQUENCY
MAX4268/70 toc18
100
1000
0 -20 CROSSTALK (dB) -40 -60 -80 -100 -120
VOLTAGE NOISE (nV/Hz)
OUTPUT IMPEDANCE ()
100
10
10
1
0.1 1 1 10 100 1k 10k 100k 1M 10M FREQUENCY (Hz) 0.01 0.1M
1M
10M FREQUENCY (Hz)
100M
1G
0.1M
1M
10M FREQUENCY (Hz)
100M
1G
MAX4268 DIFFERENTIAL GAIN AND PHASE
MAX4268/70 toc19
MAX4269 DIFFERENTIAL GAIN AND PHASE
0.020 0.010 0.000 -0.010 -0.020 -0.030 10 IRE 100 0.010
MAX4268/70 toc20
MAX4270 DIFFERENTIAL GAIN AND PHASE
0.006 0.004 0.002 0.000 -0.002 -0.004 -0.006 10 IRE 100 DIFF GAIN (%)
MAX4268/70 toc21
0.020 0.015 0.010 0.005 0.000 -0.005 10 IRE 100
DIFF GAIN (%)
0.04 0.03 0.02 0.01 0.00 -0.01 10 RL = 150 IRE 100
DIFF GAIN (%) DIFF PHASE ()
0.012 0.008 0.004 0.000 -0.004 -0.008 10 RL = 150 IRE 100
DIFF PHASE ()
DIFF PHASE ()
0.000 -0.010 -0.020 -0.030 10 RL = 150 IRE 100
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Ultra-Low-Distortion, Single-Supply, 300MHz Op Amps with Enable
Typical Operating Characteristics (continued)
(VCC = +5V, VEE = 0, EN_ = 5V, RL = 100 to VCC/2, MAX4268 AV = +1V/V, MAX4269 AV = +2V/V, MAX4270 AV = +5V/V, TA =+25C, unless otherwise noted.)
POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
MAX4268/70 toc22
MAX4265-MAX4270
COMMON-MODE REJECTION RATIO vs. FREQUENCY
MAX14268/70 toc23
OUTPUT VOLTAGE SWING vs. RESISTIVE LOAD
4.5 OUTPUT VOLTAGE SWING (V) 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 VOL 0 200 400 600 800 1000
MAX4268/70 toc24
0 -10 -20 -30 PSRR (dB) -40 -50 -60 -70 -80 -90 -100 0.1M 1M 10M FREQUENCY (Hz) 100M
0 -10 -20 -30 CMRR (dB) -40 -50 -60 -70 -80 -90
5.0 VOH
1G
10k
100k
1M
10M
100M
1G
FREQUENCY (Hz)
LOAD ()
POWER-UP/POWER-DOWN RESPONSE
MAX4268/70 toc25
SHUTDOWN/ENABLE RESPONSE
MAX4268/70 toc26
INPUT TO SHUTDOWN
5V VCC 2.5V/div
5V 0V
0V
OUTPUT 500mV/div
ENABLED
OUTPUT 500mV/div
SHUT DOWN
5s/div
250ns/div
INPUT OFFSET VOLTAGE vs. SUPPLY VOLTAGE
MAX4268/70 toc27
INPUT BIAS CURRENT vs. SUPPLY VOLTAGE
-4.5 INPUT BIAS CURRENT (A) -4.0 -3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5
MAX4268/70 toc28
-0.90 -0.95 -1.00 -1.05 -1.10 -1.15 -1.20 4.5 5.0 5.5 6.0 6.5 7.0 7.5
-5.0
INPUT OFFSET VOLTAGE (mV)
-0 8.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V)
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Ultra-Low-Distortion, Single-Supply, 300MHz Op Amps with Enable MAX4265-MAX4270
Typical Operating Characteristics (continued)
(VCC = +5V, VEE = 0, EN_ = 5V, RL = 100 to VCC/2, MAX4268 AV = +1V/V, MAX4269 AV = +2V/V, MAX4270 AV = +5V/V, TA =+25C, unless otherwise noted.)
SUPPLY CURRENT (PER AMPLIFIER) vs. SUPPLY VOLTAGE
MAX4268/70 toc29
INPUT OFFSET VOLTAGE vs. TEMPERATURE
4 INPUT OFFSET VOLTAGE (mV) 3 2 1 0 -1 -2 -3 -4 -5
MAX4268/70 toc30
35 34 33 SUPPLY CURRENT (mA) 32 31 30 29 28 27 26 25 4.5 5.0 5.5 6.0 6.5 7.0 7.5
5
8.0
-50 -35 -20 -5
10
25
40
55
70
85
SUPPLY VOLTAGE (V)
TEMPERATURE (C)
INPUT BIAS CURRENT vs. TEMPERATURE
MAX4268/70 toc31
INPUT OFFSET CURRENT vs. TEMPERATURE
400 INPUT OFFSET CURRENT (nA) 300 200 100 0 -100 -200 -300 -400
MAX4268/70 toc32
5
500
INPUT BIAS CURRENT (A)
4
3
2
1
0 -50 -35 -20 -5 10 25 40 55 70 85 TEMPERATURE (C)
-500 -50 -35 -20 -5 10 25 40 55 70 85 TEMPERATURE (C)
SUPPLY CURRENT (PER AMPLIFIER) vs. TEMPERATURE
34 33 SUPPLY CURRENT (mA) 32 31 30 29 28 27 26 25 -50 -35 -20 -5 10 25 40 55 70 85 TEMPERATURE (C) 0
MAX4268/70 toc33
VOLTAGE SWING vs. TEMPERATURE
MAX4268/70 toc34
35
5 VOH
4 VOLTAGE SWING (V)
3
2
1
VOL
-50 -35 -20 -5
10
25
40
55
70
85
TEMPERATURE (C)
8
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Ultra-Low-Distortion, Single-Supply, 300MHz Op Amps with Enable
Typical Operating Characteristics (continued)
(VCC = +5V, VEE = 0, EN_ = 5V, RL = 100 to VCC/2, MAX4268 AV = +1V/V, MAX4269 AV = +2V/V, MAX4270 AV = +5V/V, TA =+25C, unless otherwise noted.)
MAX4268 SMALL-SIGNAL PULSE RESPONSE
MAX4268/70 toc35
MAX4265-MAX4270
MAX4269 SMALL-SIGNAL PULSE RESPONSE
MAX4268/70 toc36
INPUT 50mV/div
INPUT 25mV/div
OUTPUT 50mV/div
OUTPUT 50mV/div
5ns/div
5ns/div
MAX4270 SMALL-SIGNAL PULSE RESPONSE
MAX4268/70 toc37
MAX4268 LARGE-SIGNAL PULSE RESPONSE
MAX4268/70 toc38
INPUT 10mV/div
INPUT 500mV/div
OUTPUT 50mV/div
OUTPUT 500mV/div
5ns/div
5ns/div
MAX4269 LARGE-SIGNAL PULSE RESPONSE
MAX4268/70 toc39
MAX4270 LARGE-SIGNAL PULSE RESPONSE
MAX4268/70 toc40
INPUT 250mV/div
INPUT 100mV/div
OUTPUT 500mV/div
OUTPUT 500mV/div
5ns/div
5ns/div
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9
Ultra-Low-Distortion, Single-Supply, 300MHz Op Amps with Enable MAX4265-MAX4270
Pin Description
PIN MAX4265 MAX4266 MAX4267 8 MAX/SO 1 -- 2 -- 3 -- 4, 5 6 -- 7, 8 -- MAX4268 MAX4269 MAX4270 14 SO -- 4, 5 -- 2, 9 -- 3, 10 6, 7 -- 1, 8 13, 14 11, 12 16 QSOP -- 4, 5 -- 2, 11 -- 3, 12 6, 7 -- 1, 10 15, 16 8, 9, 13, 14 EN ENA, ENB ININA-, INBIN+ INA+, INB+ VEE OUT OUTA, OUTB VCC N.C. NAME FUNCTION FUNCTION Enable Input. Active high. Connect to VCC for normal operation. Enable Input. Active high. Connect to VCC for normal operation. Inverting Input Inverting Input Noninverting Input Noninverting Input Negative Power Supply Amplifier Output Amplifier Output Positive Power Supply. Connect to a +4.5V to +8.0V supply and bypass with a 0.1F capacitor for single-supply operation. No Connection. Not internally connected.
_______________Detailed Description
The MAX4265-MAX4270 single-supply operational amplifiers feature ultra-low distortion and wide bandwidth. Their low distortion and low noise make them ideal for driving high-speed analog-to-digital converters (ADCs) up to 16 bits in telecommunications applications and high-performance signal processing. These devices can drive loads as low as 100 and deliver 45mA while maintaining DC accuracy and AC performance. The input common-mode voltage ranges from (V EE + 1.6V) to (V CC - 1.6V), while the output swings to within 1.1V of the rails.
* Choose the proper feedback-resistor and gain-resistor values for the application. In general, the smaller the closed-loop gain, the smaller the THD generated--especially when driving heavy resistive loads. Large-value feedback resistors can significantly improve distortion. The MAX4265-MAX4270's THD normally increases at approximately 20dB per decade at frequencies above 1MHz; this is a lower rate than that of comparable dual-supply op amps. * Operating the device near or above the full-power bandwidth significantly degrades distortion (see the Total Harmonic Distortion vs. Frequency graph in the Typical Operating Characteristics). * The decompensated devices (MAX4266/MAX4267/ MAX4269/MAX4270) deliver the best distortion performance since they have a slightly higher slew rate and provide a higher amount of loop gain for a given closed-loop gain setting.
Low Distortion
The MAX4265-MAX4270 use proprietary bipolar technology to achieve minimum distortion in single-supply systems--a feature typically available only in dual-supply op amps. Several factors can affect the noise and distortion that a device contributes to the input signal. The following guidelines explain how various design choices impact the total harmonic distortion (THD).
10
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Ultra-Low-Distortion, Single-Supply, 300MHz Op Amps with Enable
Choosing Resistor Values
Unity-Gain Configurations The MAX4265 and MAX4268 are internally compensated for unity gain. When configured for unity gain, they require a small resistor (RF) in series with the feedback path (Figure 1). This resistor improves AC response by reducing the Q of the tank circuit, which is formed by parasitic feedback inductance and capacitance. Inverting and Noninverting Configurations The values of the gain-setting feedback and input resistors are important design considerations. Large resistor values will increase voltage noise and interact with the amplifier's input and PC board capacitance to generate undesirable poles and zeros, which can decrease bandwidth or cause oscillations. For example, a noninverting gain of +2V/V (Figure 1) using RF = RG = 1k combined with 2pF of input capacitance and 0.5pF of board capacitance will cause a feedback pole at 128MHz. If this pole is within the anticipated amplifier bandwidth, it will jeopardize stability. Reducing the 1k resistors to 100 extends the pole frequency to 1.28GHz, but could limit output swing by adding 200 in parallel with the amplifier's load. Clearly, the selection of resistor values must be tailored to the specific application. Distortion Considerations The MAX4265-MAX4270 are ultra-low-distortion, highbandwidth op amps. Output distortion will degrade as the total load resistance seen by the amplifier decreases. To minimize distortion, keep the input and gain-setting resistor values relatively large. A 500 feedback resistor combined with an appropriate input resistor to set the gain will provide excellent AC performance without significantly increasing distortion. Noise Considerations The amplifier's input-referred noise-voltage density is dominated by flicker noise at lower frequencies and by thermal noise at higher frequencies. Because the thermal noise contribution is affected by the parallel combination of the feedback resistive network, those resistor values should be reduced in cases where the system bandwidth is large and thermal noise is dominant. This noise-contribution factor decreases, however, with increasing gain settings. For example, the input noise voltage density at the op amp input with a gain of +10V/V using R F = 100k and R G = 11k is e n = 18nV/Hz. The input noise can be reduced to 8nV/Hz by choosing RF = 1k, RG = 110.
Driving Capacitive Loads
The MAX4265-MAX4270 are not designed to drive highly reactive loads; stability is maintained with loads up to 15pF with less than 2dB peaking in the frequency response. To drive higher capacitive loads, place a small isolation resistor in series between the amplifier's output and the capacitive load (Figure 1). This resistor improves the amplifier's phase margin by isolating the capacitor from the op amp's output. To ensure a load capacitance that limits peaking to less than 2dB, select a resistance value from Figure 2. For example, if the capacitive load is 100pF, the corresponding isolation resistor is 6 (MAX4269). Figures 3 and 4 show the peaking that occurs in the frequency response with and without an isolation resistor. Coaxial cable and other transmission lines are easily driven when terminated at both ends with their characteristic impedance. When driving back-terminated transmission lines, the capacitive load of the transmission line is essentially eliminated.
MAX4265-MAX4270
ADC Input Buffer
Input buffer amplifiers can be a source of significant errors in high-speed ADC applications. The input buffer is usually required to rapidly charge and discharge the ADC's input, which is often capacitive (see Driving Capacitive Loads). In addition, since a high-speed ADC's input impedance often changes very rapidly during the conversion cycle, measurement accuracy must
RG
RF
RS* VIN CL RL
MAX4265 MAX4266 MAX4267
RF () RG ()
PART
GAIN (V/V)
MAX4265 MAX4266 MAX4267
24 500 500
500 125
1 2 5
*OPTIONAL, USED TO MINIMIZE PEAKING FOR CL > 15pF.
Figure 1. Noninverting Configuration
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11
Ultra-Low-Distortion, Single-Supply, 300MHz Op Amps with Enable MAX4265-MAX4270
be maintained using an amplifier with very low output impedance at high frequencies. The combination of high speed, fast slew rate, low noise, and a low and stable distortion over load makes the MAX4265- MAX4270 ideally suited for use as buffer amplifiers in high-speed ADC applications.
20
15 MAX4268 RISO () 10 MAX4269
Low-Power Disable Mode
The MAX4265-MAX4270 feature an active-high enable pin that can be used to save power and place the outputs in a high-impedance state. Drive EN_ with logic levels or connect EN_ to VCC for normal operation. In the dual versions (MAX4268/MAX4269/MAX4270), each individual op amp is enabled separately, allowing the devices to be used in a multiplex configuration. The supply current in low-power mode is reduced to 1.6mA per device. Enable time is typically 100ns, and disable time is typically 750s.
5 4 3 2 GAIN (dB) 1 0 -1 -2 -3 -4 -5 0.1M 1M 10M FREQUENCY (Hz) 100M 1G CL = 7.3pF CL = 2.2pF CL = 5.1pF
5
MAX4270
0 0 20 40 60 CLOAD (pF) 80 100 120
Figure 2. MAX4268/MAX4269/MAX4270 Isolation Resistance vs. Capacitive Load
5 4 3 2 GAIN (dB) 1 0 -1 -2 -3 -4 -5 0.1M 1M 10M FREQUENCY (Hz) 100M 1G CL = 2.2pF CL = 5.1pF CL = 7.3pF
Figure 3a. MAX4268 Small-Signal Gain vs. Frequency Without Isolation Resistor
4 3 2 1 GAIN (dB) 0 -1 -2 -3 -4 -5 -6 0.1M 1M 10M FREQUENCY (Hz) 100M 1G CL = 10pF CL = 7.3pF CL = 15pF
Figure 3b. MAX4269 Small-Signal Gain vs. Frequency Without Isolation Resistor
5 4 3 2 GAIN (dB) 1 0 -1 -2 -3 -4 -5 0.1M 1M 10M FREQUENCY (Hz) 100M 1G CL = 10pF RISO = 18 CL = 10pF RISO = 12 CL = 10pF RISO = 15
Figure 3c. MAX4270 Small-Signal Gain vs. Frequency Without Isolation Resistor 12
Figure 4a. MAX4268 Small-Signal Gain vs. Frequency With Isolation Resistor
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Ultra-Low-Distortion, Single-Supply, 300MHz Op Amps with Enable MAX4265-MAX4270
5 4 3 2 GAIN (dB) 1 0 -1 -2 -3 -4 -5 0.1M 1M 10M FREQUENCY (Hz) 100M 1G CL = 10pF RISO = 18 CL = 10pF RISO = 12 CL = 10pF RISO = 15 4 3 2 1 GAIN (dB) 0 -1 -2 -3 -4 -5 -6 0.1M 1M 10M FREQUENCY (Hz) 100M 1G CL = 22pF RISO = 6 CL = 22pF RISO = 22 CL = 22pF RISO = 3.9
Figure 4b. MAX4269 Small-Signal Gain vs. Frequency With Isolation Resistor
Figure 4c. MAX4270 Small-Signal Gain vs. Frequency With Isolation Resistor
Power Supplies and Layout
The MAX4265-MAX4270 operate from a single +4.5V to +8.0V power supply or from dual 2.25V to 4.0V supplies. For single-supply operation, bypass each power-supply input with a 0.1F ceramic capacitor placed close to the VCC pins, and an additional 10F to VEE. When operating from dual supplies, bypass each supply to ground. Good layout improves performance by decreasing the amount of stray capacitance and noise at the op amp's inputs and output. To decrease stray capacitance, minimize PC board trace lengths and resistor leads, and place external components close to the op amp's pins.
Chip Information
TRANSISTOR COUNT: MAX4265/66/67: 132 MAX4268/69/70: 285
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Ultra-Low-Distortion, Single-Supply, 300MHz Op Amps with Enable MAX4265-MAX4270
Pin Configurations
TOP VIEW
OUTA 1 OUTA 1 INAEN 1 IN- 2 IN+ 3 8 7 VCC VCC OUT VEE INA+ 2 3 14 VCC 13 VCC 12 N.C. INA- 2 INA+ 3 ENA 4 ENB 5 VEE 6 VEE 7 N.C. 8
16 VCC 15 VCC 14 N.C.
ENA 4 ENB 5
MAX4265 MAX4266 MAX4267
6 5
MAX4268 MAX4269 MAX4270
11 N.C. 10 INB+ 9 8 INBOUTB
MAX4268 MAX4269 MAX4270
13 N.C. 12 INB+ 11 INB10 OUTB 9 N.C.
VEE 6 VEE 7
VEE 4
MAX/SO
SO
QSOP
14
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Ultra-Low-Distortion, Single-Supply, 300MHz Op Amps with Enable
Package Information
SOICN.EPS
MAX4265-MAX4270
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8LUMAXD.EPS
15
Ultra-Low-Distortion, Single-Supply, 300MHz Op Amps with Enable MAX4265-MAX4270
Package Information (continued)
QSOP.EPS
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.
16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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