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19-3918; Rev 0; 3/06
ILABLE N KIT AVA EVALUATIO
High-Dynamic-Range, Direct Up-/Downconversion 750MHz to 1200MHz Quadrature Mod/Demod
General Description
The MAX2021 low-noise, high-linearity, direct upconversion/downconversion quadrature modulator/demodulator is designed for RFID handheld and portal readers, as well as single and multicarrier 750MHz to 1200MHz GSM/EDGE, cdma2000 (R) , WCDMA, and iDEN (R) base-station applications. Direct conversion architectures are advantageous since they significantly reduce transmitter or receiver cost, part count, and power consumption as compared to traditional IF-based double conversion systems. In addition to offering excellent linearity and noise performance, the MAX2021 also yields a high level of component integration. This device includes two matched passive mixers for modulating or demodulating in-phase and quadrature signals, two LO mixer amplifier drivers, and an LO quadrature splitter. On-chip baluns are also integrated to allow for single-ended RF and LO connections. As an added feature, the baseband inputs have been matched to allow for direct interfacing to the transmit DAC, thereby eliminating the need for costly I/Q buffer amplifiers. The MAX2021 operates from a single +5V supply. It is available in a compact 36-pin thin QFN package (6mm x 6mm) with an exposed paddle. Electrical performance is guaranteed over the extended -40C to +85C temperature range.
Features
750MHz to 1200MHz RF Frequency Range Scalable Power: External Current-Setting Resistors Provide Option for Operating Device in Reduced-Power/Reduced-Performance Mode 36-Pin, 6mm x 6mm TQFN Provides High Isolation in a Small Package Modulator Operation: Meets 4-Carrier WCDMA 65dBc ACLR +21dBm Typical OIP3 +58dBm Typical OIP2 +16.7dBm Typical OP1dB -32dBm Typical LO Leakage 43.5dBc Typical Sideband Suppression -174dBm/Hz Output Noise Density DC to 300MHz Baseband Input Allows a Direct Launch DAC Interface, Eliminating the Need for Costly I/Q Buffer Amplifiers DC-Coupled Input Allows Ability for Customer Offset Voltage Control Demodulator Operation: +35.2dBm Typical IIP3 +76dBm Typical IIP2 > 30dBm IP1dB 9.2dB Typical Conversion Loss 9.3dB Typical NF 0.06dB Typical I/Q Gain Imbalance 0.15 I/Q Typical Phase Imbalance
MAX2021
Applications
RFID Handheld and Portal Readers Single and Multicarrier WCDMA 850 Base Stations Single and Multicarrier cdmaOneTM and cdma2000 Base Stations GSM 850/GSM 900 EDGE Base Stations Predistortion Transmitters and Receivers WiMAX Transmitters and Receivers Fixed Broadband Wireless Access Military Systems Microwave Links Digital and Spread-Spectrum Communication Systems Video-on-Demand (VOD) and DOCSIS Compliant Edge QAM Modulation Cable Modem Termination Systems (CMTS)
cdma2000 is a registered trademark of Telecommunications Industry Association. iDEN is a registered trademark of Motorola, Inc. cdmaOne is a trademark of CDMA Development Group.
Ordering Information
PART MAX2021ETX MAX2021ETX-T MAX2021ETX+ TEMP RANGE -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE PKG CODE
36 Thin QFN-EP* T3666-2 (6mm x 6mm) 36 Thin QFN-EP* T3666-2 (6mm x 6mm) 36 Thin QFN-EP* T3666-2 (6mm x 6mm) 36 Thin QFN-EP* T3666-2 (6mm x 6mm)
MAX2021ETX+T -40C to +85C
*EP = Exposed paddle. + = Lead free. -T = Tape-and-reel package.
________________________________________________________________ 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.
High-Dynamic-Range, Direct Up-/Downconversion 750MHz to 1200MHz Quadrature Mod/Demod MAX2021
ABSOLUTE MAXIMUM RATINGS
VCC_ to GND ........................................................-0.3V to +5.5V BBI+, BBI-, BBQ+, BBQ- to GND...............-3.5V to (VCC + 0.3V) LO, RF to GND Maximum Current ......................................30mA RF Input Power ...............................................................+30dBm Baseband Differential I/Q Input Power (Note A) ............+20dBm LO Input Power...............................................................+10dBm RBIASLO1 Maximum Current .............................................10mA RBIASLO2 Maximum Current .............................................10mA RBIASLO3 Maximum Current .............................................10mA JA (without air flow) ......................................................34C/W JA (2.5m/s air flow) .........................................................28C/W JC (junction to exposed paddle) ...................................8.5C/W Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering 10s, non-lead free)...........+245C Lead Temperature (soldering 10s, lead free) ..................+260C
Note A: Maximum reliable continuous power applied to the baseband differential port is +20dBm from an external 100 source.
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
(MAX2021 Typical Application Circuit, VCC = +4.75V to +5.25V, GND = 0V, I/Q inputs terminated into 100 differential, LO input terminated into 50, RF output terminated into 50, 0V common-mode input, R1 = 432, R2 = 619, R3 = 332, TC = -40C to +85C, unless otherwise noted. Typical values are at VCC = +5V, VBBI = VBBQ = 1.4VP-P, fIQ = 1MHz, TC = +25C, unless otherwise noted.) (Notes 1, 2)
PARAMETER Supply Voltage Total Supply Current Total Power Dissipation SYMBOL VCC ITOTAL Pins 3, 13, 15, 31, 33 all connected to VCC CONDITIONS MIN 4.75 230 TYP 5.00 271 1355 MAX 5.25 315 1654 UNITS V mA mW
AC ELECTRICAL CHARACTERISTICS (Modulator)
(MAX2021 Typical Application Circuit, VCC = +4.75V to +5.25V, GND = 0V, I/Q differential inputs driven from a 100 DC-coupled source, 0V common-mode input, PLO = 0dBm, 750MHz fLO 1200MHz, 50 LO and RF system impedance, R1 = 432, R2 = 619, R3 = 332, TC = -40C to +85C. Typical values are at VCC = +5V, VBBI = 1.4VP-P differential, VBBQ = 1.4VP-P differential, fIQ = 1MHz, fLO = 900MHz, TC = +25C, unless otherwise noted.) (Notes 1, 2)
PARAMETER BASEBAND INPUT Baseband Input Differential Impedance BB Common-Mode Input Voltage Range LO INPUT LO Input Frequency Range LO Input Drive LO Input Return Loss I/Q MIXER OUTPUTS Output IP3 Output IP2 Output P1dB Output Power Output Power Variation Over Temperature Output-Power Flatness POUT TC = -40C to +85C Sweep fBB, PRF flatness for fBB from 1MHz to 50MHz OIP3 OIP2 fBB1 = 1.8MHz, fBB2 = 1.9MHz fBB1 = 1.8MHz, fBB2 = 1.9MHz fBB = 25MHz, PLO = 0dBm fLO = 900MHz fLO = 1000MHz 21.1 22.3 57.9 16.7 0.7 -0.016 0.15 dBm dBm dBm dBm dB/C dB RF and IF terminated (Note 3) 750 -6 12 1200 +3 MHz dBm dB fIQ = 1MHz -3.5 53 0 +3.5 V SYMBOL CONDITIONS MIN TYP MAX UNITS
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High-Dynamic-Range, Direct Up-/Downconversion 750MHz to 1200MHz Quadrature Mod/Demod
AC ELECTRICAL CHARACTERISTICS (Modulator) (continued)
(MAX2021 Typical Application Circuit, VCC = +4.75V to +5.25V, GND = 0V, I/Q differential inputs driven from a 100 DC-coupled source, 0V common-mode input, PLO = 0dBm, 750MHz fLO 1200MHz, 50 LO and RF system impedance, R1 = 432, R2 = 619, R3 = 332, TC = -40C to +85C. Typical values are at VCC = +5V, VBBI = 1.4VP-P differential, VBBQ = 1.4VP-P differential, fIQ = 1MHz, fLO = 900MHz, TC = +25C, unless otherwise noted.) (Notes 1, 2)
PARAMETER ACLR (1st Adjacent Channel 5MHz Offset) LO Leakage Sideband Suppression Output Noise Density Output Noise Floor RF Return Loss SYMBOL CONDITIONS Single-carrier WCDMA (Note 4) No external calibration, with each baseband input terminated in 50 No external calibration, fLO = 920MHz PLO = 0dBm PLO = -3dBm 30 MIN TYP 65 -32 39.6 43.5 -174 -168 15 MAX UNITS dBc dBm dBc dBm/Hz dBm/Hz dB
MAX2021
Each baseband input terminated in 50 (Note 5) POUT = 0dBm, fLO = 900MHz (Note 6) (Note 3)
AC ELECTRICAL CHARACTERISTICS (Demodulator)
(MAX2021 Typical Application Circuit when operated as a demodulator, VCC = +4.75V to +5.25V, GND = 0V, differential baseband outputs converted to a 50 single-ended output, PRF = PLO = 0dBm, 750MHz fLO 1200MHz, 50 LO and RF system impedance, R1 = 432, R2 = 619, R3 = 332, TC = -40C to +85C. Typical values are at VCC = +5V, TC = +25C, unless otherwise noted.) (Notes 1, 2)
PARAMETER RF INPUT RF Frequency Conversion Loss Noise Figure Noise Figure Under-Blocking Input Third-Order Intercept Input Second-Order Intercept Input 1dB Compression I/Q Gain Mismatch I/Q Phase Mismatch fRF LC NF NFBLOCK IIP3 IIP2 P1dB fBB = 25MHz (Note 7) fLO = 900MHz fBLOCKER = 900MHz, PRF = 11dBm, fRF = fLO = 890MHz (Note 8) fRF1 = 925MHz, fRF2 = 926MHz, fLO = 900MHz, PRF = PLO = 0dBm, fSPUR = 24MHz fRF1 = 925MHz, fRF2 = 926MHz, fLO = 900MHz, PRF = PLO = 0dBm, fSPUR = 51MHz fIF = 50MHz, fLO = 900MHz, PLO = 0dBm fBB = 1MHz, fLO = 900MHz, PLO = 0dBm fBB = 1MHz, fLO = 900MHz PLO = 0dBm PLO = -3dBm 750 9.2 9.3 17.8 35.2 76 30 0.06 1.1 0.15 1200 MHz dB dB dB dBm dBm dBm dB degrees SYMBOL CONDITIONS MIN TYP MAX UNITS
Note 1: Guaranteed by design and characterization. Note 2: TC is the temperature on the exposed paddle. Note 3: Parameter also applies to demodulator topology. Note 4: Single-carrier WCDMA with 10.5dB peak-to-average ratio at 0.1% complementary cumulative distribution function, PRF = -10dBm (PRF is chosen to give -65dBc ACLR). Note 5: No baseband drive input. Measured with the inputs terminated in 50. At low output levels, the output noise is thermal. Note 6: The output noise versus POUT curve has the slope of LO noise (Ln dBc/Hz) due to reciprocal mixing. Note 7: Conversion loss is measured from the single-ended RF input to single-ended combined baseband output. Note 8: The LO noise (L = 10(Ln/10)), determined from the modulator measurements can be used to deduce the noise figure underblocking at operating temperature (Tp in Kelvin), FBLOCK = 1 + (Lcn - 1) Tp / To + LPBLOCK / (1000kTo), where To = 290K, PBLOCK in mW, k is Boltzmann's constant = 1.381 x 10(-23) J/K, and Lcn = 10(Lc/10), Lc is the conversion loss. Noise figure under-blocking in dB is NFBLOCK = 10 x log (FBLOCK). Refer to Application Note 3632. _______________________________________________________________________________________ 3
High-Dynamic-Range, Direct Up-/Downconversion 750MHz to 1200MHz Quadrature Mod/Demod MAX2021
Typical Operating Characteristics
(MAX2021 Typical Application Circuit, VCC = +4.75V to +5.25V, GND = 0V, I/Q differential inputs driven from a 100 DC-coupled source, 0V common-mode input, PLO = 0dBm, 750MHz fLO 1200MHz, 50 LO and RF system impedance, R1 = 432, R2 = 619, R3 = 332, TC = -40C to +85C. Typical values are at VCC = +5V, VBBI = 1.4VP-P differential, VBBQ = 1.4VP-P differential, fIQ = 1MHz, fLO = 900MHz, TC = +25C, unless otherwise noted.)
TOTAL SUPPLY CURRENT vs. TEMPERATURE (TC)
MAX2021 toc01
MODULATOR
ACLR vs. OUTPUT POWER PER CARRIER
MAX2021 toc02
ACLR vs. OUTPUT POWER PER CARRIER
-62 -64 -66 ACLR (dB) ADJACENT CHANNEL
MAX2021 toc03
300 VCC = 5.25V
-60 -62 -64 -66 ACLR (dB)
-60
TOTAL SUPPLY CURRENT (mA)
280
260 VCC = 5.0V 240 VCC = 4.75V 220
-68 -70 -72 -74 -76 -78
ADJACENT CHANNEL
-68 -70 -72 -74 -76 ALTERNATE CHANNEL
ALTERNATE CHANNEL
200 -40 -15 10 35 60 85 TEMPERATURE (C)
-80
SINGLE-CARRIER WCDMA -47 -37 -27 -17 -7
-78 -80 TWO-CARRIER WCDMA -47 -37 -27 -17 -7
OUTPUT POWER PER CARRIER (dBm)
OUTPUT POWER PER CARRIER (dBm)
ACLR vs. OUTPUT POWER PER CARRIER
-62 -64 -66 ACLR (dB) -68 -70 -72 -74 -76 -78 -80 FOUR-CARRIER WCDMA -47 -37 -27 -17 -7 ALTERNATE CHANNEL
MAX2021 toc04
SIDEBAND SUPPRESSION vs. LO FREQUENCY
PLO = -6dBm
MAX2021 toc05
SIDEBAND SUPPRESSION vs. LO FREQUENCY
MAX2021 toc06
-60 ADJACENT CHANNEL
70 SIDEBAND SUPPRESSION (dBc) 60 50 40 30 20 PLO = +3dBm 10 750 825 900 975 1050 1125 PLO = -3dBm
70 SIDEBAND SUPPRESSION (dBc) 60 50 40 30 20 10 VCC = 4.75V, 5.0V, 5.25V
PLO = 0dBm
1200
750
825
900
975
1050
1125
1200
OUTPUT POWER PER CARRIER (dBm)
LO FREQUENCY (MHz)
LO FREQUENCY (MHz)
SIDEBAND SUPPRESSION vs. LO FREQUENCY
MAX2021 toc07
OUTPUT IP3 vs. LO FREQUENCY
PLO = 0dBm, VCC = 5.0V 25 OUTPUT IP3 (dBm) TC = -40C TC = +25C 20 TC = +85C 15
MAX2021 toc08
OUTPUT IP3 vs. LO FREQUENCY
TC = +25C VCC = 5.25V 25 OUTPUT IP3 (dBm)
MAX2021 toc09
70 SIDEBAND SUPPRESSION (dBc) 60 50 40 30 20 10 750 825 900 975 1050 1125 TC = +25C TC = -40C TC = +85C
30
30
20
VCC = 5.0V VCC = 4.75V
15
10 1200 750 825 900 975 1050 1125 1200 LO FREQUENCY (MHz) LO FREQUENCY (MHz)
10 750 825 900 975 1050 1125 1200 LO FREQUENCY (MHz)
4
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High-Dynamic-Range, Direct Up-/Downconversion 750MHz to 1200MHz Quadrature Mod/Demod MAX2021
Typical Operating Characteristics (continued)
(MAX2021 Typical Application Circuit, VCC = +4.75V to +5.25V, GND = 0V, I/Q differential inputs driven from a 100 DC-coupled source, 0V common-mode input, PLO = 0dBm, 750MHz fLO 1200MHz, 50 LO and RF system impedance, R1 = 432, R2 = 619, R3 = 332, TC = -40C to +85C. Typical values are at VCC = +5V, VBBI = 1.4VP-P differential, VBBQ = 1.4VP-P differential, fIQ = 1MHz, fLO = 900MHz, TC = +25C, unless otherwise noted.)
MODULATOR
OUTPUT IP3 vs. LO FREQUENCY
MAX2021 toc10
OUTPUT IP3 vs. COMMON-MODE VOLTAGE
MAX2021 toc11
OUTPUT IP3 vs. COMMON-MODE VOLTAGE
fLO = 1000MHz 25 OUTPUT IP3 (dBm) 24 23 22 21 20
MAX2021 toc12
30 TC = +25C PLO = -3dBm 25 OUTPUT IP3 (dBm) PLO = +3dBm
26 fLO = 900MHz, PLO = 0dBm 25 OUTPUT IP3 (dBm) 24 23 22 21
26
20 PLO = -6dBm
15
PLO = 0dBm
10 750 825 900 975 1050 1125 1200 LO FREQUENCY (MHz)
20 -3.50 -1.75 0 1.75 3.50 COMMON-MODE VOLTAGE (V)
-3.50
-1.75
0
1.75
3.50
COMMON-MODE VOLTAGE (V)
OUTPUT IP2 vs. LO FREQUENCY
MAX2021 toc13
OUTPUT IP2 vs. LO FREQUENCY
MAX2021 toc14
OUTPUT IP2 vs. LO FREQUENCY
MAX2021 toc15
80 TC = -40C 70 OUTPUT IP2 (dBm)
80 VCC = 5.25V 70 OUTPUT IP2 (dBm)
80
70 OUTPUT IP2 (dBm)
PLO = +3dBm
TC = +25C 60
60
VCC = 5.0V
60
PLO = -6dBm
50 TC = +85C 40 750 825 900 975 1050 1125 1200 LO FREQUENCY (MHz)
50 VCC = 4.75V 40 750 825 900 975 1050 1125 1200 LO FREQUENCY (MHz)
50
PLO = 0dBm PLO = -3dBm
40 750 825 900 975 1050 1125 1200 LO FREQUENCY (MHz)
OUTPUT IP2 vs. COMMON-MODE VOLTAGE
MAX2021 toc16
OUTPUT IP2 vs. COMMON-MODE VOLTAGE
MAX2021 toc17
MODULATOR OUTPUT POWER vs. INPUT POWER
INPUT SPLIT BETWEEN I AND Q, fIF = 25MHz, fLO = 900MHz 15 OUTPUT POWER (dBm)
MAX2021 toc18
80
fLO = 900MHz
70
fLO = 1000MHz
20
75 OUTPUT IP2 (dBm)
65 OUTPUT IP2 (dBm) 70
10
60
65
5 VCC = 4.75V, 5.0V, 5.25V 0
60
55
55 -3.50 -1.75 0 1.75 3.50 COMMON-MODE VOLTAGE (V)
50 -3.50 -1.75 0 1.75 3.50 COMMON-MODE VOLTAGE (V)
-5 10 13 16 19 22 25 28 INPUT POWER (dBm)
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High-Dynamic-Range, Direct Up-/Downconversion 750MHz to 1200MHz Quadrature Mod/Demod MAX2021
Typical Operating Characteristics (continued)
(MAX2021 Typical Application Circuit, VCC = +4.75V to +5.25V, GND = 0V, I/Q differential inputs driven from a 100 DC-coupled source, 0V common-mode input, PLO = 0dBm, 750MHz fLO 1200MHz, 50 LO and RF system impedance, R1 = 432, R2 = 619, R3 = 332, TC = -40C to +85C. Typical values are at VCC = +5V, VBBI = 1.4VP-P differential, VBBQ = 1.4VP-P differential, fIQ = 1MHz, fLO = 900MHz, TC = +25C, unless otherwise noted.)
MODULATOR
MODULATOR OUTPUT POWER vs. INPUT POWER
MAX2021 toc19
MODULATOR OUTPUT POWER vs. LO FREQUENCY
MAX2021 toc20
LO LEAKAGE vs. LO FREQUENCY
LO LEAKAGE NULLED AT PRF = -1dBm PRF = -40dBm PRF = +5dBm
MAX2021 toc21 MAX2021 toc24
20 INPUT SPLIT BETWEEN I AND Q, fIF = 25MHz, fLO = 900MHz 15 OUTPUT POWER (dBm)
5
VBBI = VBBQ = 1.4VP-P DIFFERENTIAL TC = -40C
-40 -50 LO LEAKAGE (dBm) -60 -70 -80 -90 -100
3 OUTPUT POWER (dBm)
10
1
PRF = -7dBm
5 PLO = -6dBm, -3dBm, 0dBm, +3dBm
-1
TC = +85C
TC = +25C
0
-3
-5 10 13 16 19 22 25 28 INPUT POWER (dBm)
-5 750 825 900 975 1050 1125 1200 LO FREQUENCY (MHz)
PRF = -1dBm 915 926 937 948 959 970
LO FREQUENCY (MHz)
LO LEAKAGE vs. LO FREQUENCY
MAX2021 toc22
LO LEAKAGE vs. LO FREQUENCY
MAX2021 toc23
OUTPUT NOISE vs. OUTPUT POWER
-150 -155 OUTPUT NOISE (dBm/Hz) PLO = -6dBm -160 PLO = -3dBm -165 -170 PLO = 0dBm -175 PLO = +3dBm -180 TC = +25C, fLO = 900MHz
-40 -50 LO LEAKAGE (dBm) -60 -70 -80 -90 -100
PRF = -1dBm, LO LEAKAGE NULLED AT TC = +25C
-40 -50 LO LEAKAGE (dBm) -60 -70 -80 -90
PRF = -1dBm, LO LEAKAGE NULLED AT PLO = 0dBm
TC = -40C
PLO = -6dBm
PLO = -3dBm
TC = +85C
PLO = +3dBm
TC = +25C 915 926 937 948 959 970 LO FREQUENCY (MHz)
-100 915 926
PLO = 0dBm 937 948 959 970
-15
-10
-5
0
5
10
15
LO FREQUENCY (MHz)
OUTPUT POWER (dBm)
OUTPUT NOISE vs. OUTPUT POWER
PLO = 0dBm, fLO = 900MHz
MAX2021 toc25
-150 -155 OUTPUT NOISE (dBm/Hz) -160 -165 -170 -175
TC = +85C
TC = -40C TC = +25C
-180 -15 -10 -5 0 5 10 15 OUTPUT POWER (dBm)
6
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High-Dynamic-Range, Direct Up-/Downconversion 750MHz to 1200MHz Quadrature Mod/Demod
Typical Operating Characteristics
(MAX2021 Typical Application Circuit, VCC = +4.75V to +5.25V, GND = 0V, I/Q differential inputs driven from a 100 DC-coupled source, 0V common-mode input, PRF = 5dBm, PLO = 0dBm, 750MHz fLO 1200MHz, 50 LO and RF system impedance, R1 = 432, R2 = 619, R3 = 332, TC = -40C to +85C. Typical values are at VCC = +5V, fLO = 900MHz, TC = +25C, unless otherwise noted.)
MAX2021
DEMODULATOR
DEMODULATOR CONVERSION LOSS vs. LO FREQUENCY
MAX2021 toc26
DEMODULATOR INPUT IP3 vs. LO FREQUENCY
MAX2021 toc27
DEMODULATOR INPUT IP3 vs. LO FREQUENCY
PLO = 0dBm, VCC = 5.0V TC = +25C TC = -40C 36
MAX2021 toc28
12 DEMODULATOR CONVERSION LOSS (dB)
PLO = 0dBm, VCC = 5.0V TC = +25C TC = +85C
40 DEMODULATOR INPUT IP3 (dBm)
PLO = 0dBm, TC = +25C VCC = 5.25V
40 DEMODULATOR INPUT IP3 (dBm)
11
38
38
10
36
9
34
VCC = 5.0V
34
8
TC = -40C
32 VCC = 4.75V 30
32 TC = +85C 30
7 750 825 900 975 1050 1125 1200 LO FREQUENCY (MHz)
750
825
900
975
1050
1125
1200
750
825
900
975
1050
1125
1200
LO FREQUENCY (MHz)
LO FREQUENCY (MHz)
DEMODULATOR INPUT IP2 vs. LO FREQUENCY
MAX2021 toc29
DEMODULATOR PHASE IMBALANCE vs. LO FREQUENCY
MAX2021 toc30
DEMODULATOR AMPLITUDE IMBALANCE vs. LO FREQUENCY
DEMODULATOR AMPLITUDE IMBALANCE (dB) 0.15 0.10 0.05 0 -0.05 -0.10 -0.15 -0.20 750 825 900 975 1050 1125 LO FREQUENCY (MHz) 1200 PLO = -6dBm, -3dBm, 0dBm, +3dBm
MAX2021 toc31
90 PLO = 0dBm, VCC = 5.0V DEMODULATOR INPUT IP2 (dBm) 80 TC = +25C 70 TC = +85C 60 TC = -40C 50 750 825 900 975 1050 1125
10 DEMODULATOR PHASE IMBALANCE (deg) 8 6 4 2 0 -2 -4 -6 -8 -10 750 825
PLO = +3dBm PLO = -3dBm PLO = 0dBm
0.20
PLO = -6dBm
1200
900
975
1050
1125
1200
LO FREQUENCY (MHz)
LO FREQUENCY (MHz)
LO PORT RETURN LOSS vs. LO FREQUENCY
MAX2021 toc32
RF PORT RETURN LOSS vs. LO FREQUENCY
MAX2021 toc33
IF FLATNESS vs. BASEBAND FREQUENCY
PLO = 0dBm fLO = 900MHz -5 IF OUTPUT POWER (dBm) -6 -7 -8 -9 -10 -11 -12 0 10 20 30 40 50 60 70 80 fLO = 1000MHz
MAX2021 toc34
0 PLO = +3dBm LO PORT RETURN LOSS (dB) +5 PLO = 0dBm +10
0 +5 RF PORT RETURN LOSS (dB) +10 +15 +20 +25 +30 +35 +40 PLO = -6dBm, -3dBm, 0dBm, +3dBm
-4
+15 PLO = -6dBm, -3dBm +20
+25 750 825 900 975 1050 1125 1200 LO FREQUENCY (MHz)
+45 750 845 940 1035 1130 1225 LO FREQUENCY (MHz)
BASEBAND FREQUENCY (MHz)
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7
High-Dynamic-Range, Direct Up-/Downconversion 750MHz to 1200MHz Quadrature Mod/Demod MAX2021
Pin Description
PIN 1, 5, 9-12, 14, 16-19, 22, 24, 27-30, 32, 34, 35, 36 2 3 4 6 7 8 13 15 20 21 23 25 26 31 33 EP NAME GND Ground FUNCTION
RBIASLO3 3rd LO Amplifier Bias. Connect a 332 resistor to ground. VCCLOA LO N.C. LO Input Buffer Amplifier Supply Voltage. Bypass to GND with 33pF and 0.1F capacitors as close to the pin as possible. Local Oscillator Input. 50 input impedance. No Connection. Leave unconnected. I-Channel 1st LO Amplifier Supply Voltage. Bypass to GND with 33pF and 0.1F capacitors as close to the pin as possible. I-Channel 2nd LO Amplifier Supply Voltage. Bypass to GND with 33pF and 0.1F capacitors as close to the pin as possible. Baseband In-Phase Noninverting Port Baseband In-Phase Inverting Port RF Port Baseband Quadrature Inverting Port Baseband Quadrature Noninverting Port Q-Channel 2nd LO Amplifier Supply Voltage. Bypass to GND with 33pF and 0.1F capacitors as close to the pin as possible. Q-Channel 1st LO Amplifier Supply Voltage. Bypass to GND with 33pF and 0.1F capacitors as close to the pin as possible. Exposed Ground Paddle. The exposed paddle MUST be soldered to the ground plane using multiple vias.
RBIASLO1 1st LO Input Buffer Amplifier Bias. Connect a 432 resistor to ground. RBIASLO2 2nd LO Amplifier Bias. Connect a 619 resistor to ground. VCCLOI1 VCCLOI2 BBI+ BBIRF BBQBBQ+ VCCLOQ2 VCCLOQ1 GND
Detailed Description
The MAX2021 is designed for upconverting differential in-phase (I) and quadrature (Q) inputs from baseband to a 750MHz to 1200MHz RF frequency range. The device can also be used as a demodulator, downconverting an RF input signal directly to baseband. Applications include RFID handheld and portal readers, as well as single and multicarrier GSM/EDGE, cdma2000, WCDMA, and iDEN base stations. Direct conversion architectures are advantageous since they significantly reduce transmitter or receiver cost, part count, and power consumption as compared to traditional IF-based double conversion systems. The MAX2021 integrates internal baluns, an LO buffer, a phase splitter, two LO driver amplifiers, two matched double-balanced passive mixers, and a wideband quadrature combiner. The MAX2021's high-linearity mixers, in conjuction with the part's precise in-phase and quadrature channel matching, enable the device to possess excellent dynamic range, ACLR, 1dB compression
8
point, and LO and sideband suppression characteristics. These features make the MAX2021 ideal for fourcarrier WCDMA operation.
LO Input Balun, LO Buffer, and Phase Splitter
The MAX2021 requires a single-ended LO input, with a nominal power of 0dBm. An internal low-loss balun at the LO input converts the single-ended LO signal to a differential signal at the LO buffer input. In addition, the internal balun matches the buffer's input impedance to 50 over the entire band of operation. The output of the LO buffer goes through a phase splitter, which generates a second LO signal that is shifted by 90 with respect to the original. The 0 and 90 LO signals drive the I and Q mixers, respectively.
LO Driver
Following the phase splitter, the 0 and 90 LO signals are each amplified by a two-stage amplifier to drive the I and Q mixers. The amplifier boosts the level of the LO
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High-Dynamic-Range, Direct Up-/Downconversion 750MHz to 1200MHz Quadrature Mod/Demod
signals to compensate for any changes in LO drive levels. The two-stage LO amplifier allows a wide input power range for the LO drive. The MAX2021 can tolerate LO level swings from -6dBm to +3dBm. transmitter lineup, with minimal ancillary circuit elements. Such DACs include the MAX5875 series of dual DACs, and the MAX5895 dual interpolating DAC. These DACs have ground-referenced differential current outputs. Typical termination of each DAC output into a 50 load resistor to ground, and a 10mA nominal DC output current results in a 0.5V common-mode DC level into the modulator I/Q inputs. The nominal signal level provided by the DACs will be in the -12dBm range for a single CDMA or WCDMA carrier, reducing to -18dBm per carrier for a four-carrier application. The I/Q input bandwidth is greater than 50MHz at -0.1dB response. The direct connection of the DAC to the MAX2021 ensures the maximum signal fidelity, with no performance-limiting baseband amplifiers required. The DAC output can be passed through a lowpass filter to remove the image frequencies from the DAC's output response. The MAX5895 dual interpolating DAC can be operated at interpolation rates up to x8. This has the benefit of moving the DAC image frequencies to a very high, remote frequency, easing the design of the baseband filters. The DAC's output noise floor and interpolation filter stopband attenuation are sufficiently good to ensure that the 3GPP noise floor requirement is met for large frequency offsets, 60MHz for example, with no filtering required on the RF output of the modulator. Figure 1 illustrates the ease and efficiency of interfacing the MAX2021 with a Maxim DAC, in this case the MAX5895 dual 16-bit interpolating-modulating DAC.
MAX2021
I/Q Modulator
The MAX2021 modulator is composed of a pair of matched double-balanced passive mixers and a balun. The I and Q differential baseband inputs accept signals from DC to 300MHz with differential amplitudes up to 4VP-P. The wide input bandwidths allow operation of the MAX2021 as either a direct RF modulator or as an image-reject mixer. The wide common-mode compliance range allows for direct interface with the baseband DACs. No active buffer circuitry is required between the baseband DACs and the MAX2021 for cdma2000 and WCDMA applications. The I and Q signals directly modulate the 0 and 90 LO signals and are upconverted to the RF frequency. The outputs of the I and Q mixers are combined through a balun to produce a singled-ended RF output.
Applications Information
LO Input Drive
The LO input of the MAX2021 is internally matched to 50, and requires a single-ended drive at a 750MHz to 1200MHz frequency range. An integrated balun converts the singled-ended input signal to a differential signal at the LO buffer differential input. An external DC-blocking capacitor is the only external part required at this interface. The LO input power should be within the -6dBm to +3dBm range. An LO input power of -3dBm is recommended for best overall peformance.
Baseband I/Q Input Drive
Drive the MAX2021 I and Q baseband inputs differentially for best performance. The baseband inputs have a 53 differential input impedance. The optimum source impedance for the I and Q inputs is 100 differential. This source impedance achieves the optimal signal transfer to the I and Q inputs, and the optimum output RF impedance match. The MAX2021 can accept input power levels of up to +20dBm on the I and Q inputs. Operation with complex waveforms, such as CDMA carriers or GSM signals, utilize input power levels that are far lower. This lower power operation is made necessary by the high peak-to-average ratios of these complex waveforms. The peak signals must be kept below the compression level of the MAX2021. The input common-mode voltage should be confined to the -3.5V to +3.5V DC range. The MAX2021 is designed to interface directly with Maxim high-speed DACs. This generates an ideal total
BBI
MAX5895 DUAL 16-BIT INTERP DAC
MAX2021
50 RF MODULATOR
FREQ 50
I/Q GAIN AND OFFSET ADJUST
LO
0 90
50
BBQ
FREQ
50
Figure 1. MAX5895 DAC Interfaced with MAX2021 9
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High-Dynamic-Range, Direct Up-/Downconversion 750MHz to 1200MHz Quadrature Mod/Demod MAX2021
The MAX5895 DAC has programmable gain and differential offset controls built in. These can be used to optimize the LO leakage and sideband suppression of the MAX2021 quadrature modulator. mised by an improperly terminated I/Q IF interface. Care must be taken to match the I/Q ports to the driving DAC circuitry. Without matching, the LO's second-order (2fLO) term may leak back into the modulator's I/Q input port where it can mix with the internal LO signal to produce additional LO leakage at the RF output. This leakage effectively counteracts against the LO nulling. In addition, the LO signal reflected at the I/Q IF port produces a residual DC term that can disturb the nulling condition. As demonstrated in Figure 2, providing an RC termination on each of the I+, I-, Q+, Q- ports reduces the amount of LO leakage present at the RF port under varying temperature, LO frequency, and baseband drive conditions. See the Typical Operating Characteristics for details. Note that the resistor value is chosen to be 100 with a corner frequency 1 / (2RC) selected to adequately filter the fLO and 2fLO leakage, yet not affecting the flatness of the baseband response at the highest baseband frequency. The common-mode fLO and 2fLO signals at I+/I- and Q+/Q- effectively see the RC networks and thus become terminated in 50 (R/2). The RC network provides a path for absorbing the 2fLO and fLO leakage, while the inductor provides high impedance at fLO and 2fLO to help the diplexing process.
MAX2021 MAX2021
RF Output
The MAX2021 utilizes an internal passive mixer architecture that enables the device to possess an exceptionally low-output noise floor. With such architectures, the total output noise is typically a power summation of the theoretical thermal noise (KTB) and the noise contribution from the on-chip LO buffer circuitry. As demonstrated in the Typical Operating Characteristics, the MAX2021's output noise approaches the thermal limit of -174dBm/Hz for lower output power levels. As the output power increases, the noise level tracks the noise contribution from the LO buffer circuitry, which is approximately -168dBc/Hz. The I/Q input power levels and the insertion loss of the device determine the RF output power level. The input power is a function of the delivered input I and Q voltages to the internal 50 termination. For simple sinusoidal baseband signals, a level of 89mVP-P differential on the I and the Q inputs results in a -17dBm input power level delivered to the I and Q internal 50 terminations. This results in an RF output power of -23.2dBm.
RF Demodulator
The MAX2021 can also be used as an RF demodulator, downconverting an RF input signal directly to baseband. The single-ended RF input accepts signals from 750MHz to 1200MHz with power levels up to +30dBm. The passive mixer architecture produces a conversion loss of typically 9.2dB. The downconverter is optimized for high linearity and excellent noise performance, typically with a +35.2dBm IIP3, a P1dB of greater than +30dBm, and a 9.3dB noise figure. A wide I/Q port bandwidth allows the port to be used as an image-reject mixer for downconversion to a quadrature IF frequency. The RF and LO inputs are internally matched to 50. Thus, no matching components are required, and only DC-blocking capacitors are needed for interfacing.
External Diplexer
LO leakage at the RF port can be nulled to a level less than -80dBm by introducing DC offsets at the I and Q ports. However, this null at the RF port can be comproC = 6.8pF
100 I L = 40nH
MAX2021
RF-MODULATOR
100
C = 6.8pF
LO
0 90
100 Q L = 40nH
Power Scaling with Changes to the Bias Resistors
Bias currents for the LO buffers are optimized by fine tuning resistors R1, R2, and R3. Maxim recommends using 1%-tolerant resistors; however, standard 5% values can be used if the 1% components are not readily available. The resistor values shown in the Typical Application Circuit were chosen to provide peak performance for the entire 750MHz to 1200MHz band. If desired, the current can be backed off from this nominal value by choosing different values for R1,
100
C = 6.8pF
Figure 2. Diplexer Network Recommended for GSM 900 Transmitter Applications 10
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High-Dynamic-Range, Direct Up-/Downconversion 750MHz to 1200MHz Quadrature Mod/Demod MAX2021
Table 1. Typical Performance Trade-Offs as a Function of Current Draw--Modulator Mode
LO FREQ (MHz) RF FREQ (MHz) R1 () 420 453 800 801.8 499 549 650 420 453 900 901.8 499 549 650 420 453 1000 1001.8 499 549 650 R2 () 620 665 698 806 1000 620 665 698 806 1000 620 665 698 806 1000 R3 () 330 360 402 464 550 330 360 402 464 550 330 360 402 464 550 ICC (mA) 271 253 229 205 173 271 253 229 205 173 271 253 229 205 173 OIP3 (dBm) 19.6 21.9 18.9 15.7 13.6 20.7 21.6 20.6 19.0 14.9 22.4 22.2 19.9 17.6 14.6 LO LEAK (dBm) -32.1 -32.7 -33.7 -34.4 -34.2 -31.4 -31.6 -31.8 -31.9 -30.5 -32.8 -33.2 -33.8 -34.8 -33.9 IMAGE REJ (dBc) 23.9 34.0 30.0 23.7 23.3 43.4 42.4 42.7 40.3 25.0 39.3 39.1 43.5 40.5 36.8 OIP2 (dBm) 50.5 51.0 52.6 46.0 32.3 54.0 55.4 59.8 50.7 34.6 55.5 56.3 55.0 51.4 32.8
Note: VCC = 5V, PLO = 0dBm, TA = +25C, I/Q voltage levels = 1.4VP-P differential.
R2, and R3. Tables 1 and 2 outline the performance trade-offs that can be expected for various combinations of these bias resistors. As noted within the tables, the performance trade-offs may be more pronounced for different operating frequencies. Contact the factory for additional details.
33pF and 0.1F capacitors placed as close to the pins as possible. The smallest capacitor should be placed closest to the device. To achieve optimum performance, use good voltagesupply layout techniques. The MAX2021 has several RF processing stages that use the various VCC_ pins, and while they have on-chip decoupling, off-chip interaction between them may degrade gain, linearity, carrier suppression, and output power-control range. Excessive coupling between stages may degrade stability.
Layout Considerations
A properly designed PC board is an essential part of any RF/microwave circuit. Keep RF signal lines as short as possible to reduce losses, radiation, and inductance. For the best performance, route the ground pin traces directly to the exposed pad under the package. The PC board exposed paddle MUST be connected to the ground plane of the PC board. It is suggested that multiple vias be used to connect this pad to the lowerlevel ground planes. This method provides a good RF/thermal conduction path for the device. Solder the exposed pad on the bottom of the device package to the PC board. The MAX2021 evaluation kit can be used as a reference for board layout. Gerber files are available upon request at www.maxim-ic.com.
Exposed Pad RF/Thermal Considerations
The EP of the MAX2021's 36-pin thin QFN-EP package provides a low thermal-resistance path to the die. It is important that the PC board on which the IC is mounted be designed to conduct heat from this contact. In addition, the EP provides a low-inductance RF ground path for the device. The exposed paddle (EP) MUST be soldered to a ground plane on the PC board either directly or through an array of plated via holes. An array of 9 vias, in a 3 x 3 array, is suggested. Soldering the pad to ground is critical for efficient heat transfer. Use a solid ground plane wherever possible.
Power-Supply Bypassing
Proper voltage-supply bypassing is essential for highfrequency circuit stability. Bypass all VCC_ pins with
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11
High-Dynamic-Range, Direct Up-/Downconversion 750MHz to 1200MHz Quadrature Mod/Demod MAX2021
Table 2. Typical Performance Trade-Offs as a Function of Current Draw--Demodulator Mode
LO FREQ (MHz) RF FREQ (MHz) R1 () 420 453 800 771 499 549 650 420 453 900 871 499 549 650 420 453 1000 971 499 549 650 R2 () 620 665 698 806 1000 620 665 698 806 1000 620 665 698 806 1000 R3 () 330 360 402 464 550 330 360 402 464 550 330 360 402 464 550 ICC (mA) 269 254 230 207 173 269 254 230 207 173 269 254 230 207 173 CONVERSION LOSS (dB) 9.8 9.83 9.81 9.84 9.95 9.21 9.25 9.36 9.39 9.46 9.47 9.5 9.53 9.5 9.61 IIP3 (dBm) 33.85 33.98 32.2 31.1 29.87 33.1 33.9 34.77 35.3 32 34.9 35.4 34.58 33.15 31.5 57MHz IIP2 (dBm) 62.1 62.9 66.6 66.86 65.25 68 66.87 66.7 66.6 64.64 > 77.7 > 77.5 > 76.5 > 76.5 76
Note: Used on PC board 180 combiners and off PC board quadrature combiner with VCC = 5V, PRF = -3dBm, PLO = 0dBm, TA = +25C, IF1 = 28MHz, IF2 = 29MHz.
12
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High-Dynamic-Range, Direct Up-/Downconversion 750MHz to 1200MHz Quadrature Mod/Demod
Pin Configuration/Functional Diagram
VCCLOQ1 VCCLOQ2
MAX2021 MAX2021
GND
GND
GND
GND
29
GND
GND
36 GND RBIASLO3 VCCLOA LO GND RBIASLO1 N.C. RBIASLO2 GND 1 2 3 4 5 6 7 8 9 10
35
34
33
32
31
30
28 27 26 25 GND BBQ+ BBQGND RF GND BBIBBI+ GND
BIAS LO3
MAX2021
90 0
GND
24 23 22 21 20 19 18
BIAS LO1
BIAS LO2
11
12
13
14
15
16
17
GND
GND
VCCLOI1
VCCLOI2
GND
GND
GND
THIN QFN
______________________________________________________________________________________
GND
GND
13
High-Dynamic-Range, Direct Up-/Downconversion 750MHz to 1200MHz Quadrature Mod/Demod MAX2021
Typical Application Circuit
VCCLOQ1
VCC
C12 0.1F
C13 33pF VCCLOQ2
C10 33pF
C11 0.1F VCC
R3 332 GND RBIASLO3 VCC C2 0.1F C1 33pF C3 82pF VCCLOA LO GND RBIASLO1 R1 432 N.C. RBIASLO2 R2 619 GND 1 2 3 4 5 6 7 8 9
GND 36
GND 35
GND 34 33
GND 32
GND 30
GND 29 28
GND
31
BIAS LO3
MAX2021
27 26 25
GND BBQ+ BBQGND Q+ QC9 8.2pF RF
90 0
24
23 RF BIAS LO1
22 21
GND BBIBBI+ GND II+
BIAS LO2
20 19
10 GND VCC
11 GND
12 GND
13 VCCLOI1
14 GND
15 VCCLOI2
16 GND
17 GND
18 GND VCC
C5 0.1F
C6 33pF
C7 33pF
C8 0.1F
Table 3. Component List Referring to the Typical Application Circuit
COMPONENT C1, C6, C7, C10, C13 C2, C5, C8, C11, C12 C3 C9 R1 R2 R3 VALUE 33pF 0.1F 82pF 8.2pF 432 619 332 DESCRIPTION 33pF 5%, 50V C0G ceramic capacitors (0402) 0.1F 10%, 16V X7R ceramic capacitors (0603) 82pF 5%, 50V C0G ceramic capacitor (0402) 8.2pF 0.1pF, 50V C0G ceramic capacitor (0402) 432 1% resistor (0402) 619 1% resistor (0402) 332 1% resistor (0402)
Chip Information
PROCESS: SiGe BiCMOS
Package Information
For the latest package outline information, go to www.maxim-ic.com/packages.
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.
14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2006 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.

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