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19-4786; Rev 1; 11/98
ANUAL N KIT M LUATIO ATA SHEET EVA WS D FOLLO
400MHz to 2.5GHz, Low-Noise, SiGe Downconverter Mixers
Features
o 400MHz to 2.5GHz Operation o +2.7V to +5.5V Single-Supply Operation o Low Noise Figure: 6.3dB at 900MHz (MAX2680) o High Input Third-Order Intercept Point (IIP3 at 2450MHz) -6.9dBm at 5.0mA (MAX2680) +1.0dBm at 8.7mA (MAX2681) +3.2dBm at 15.0mA (MAX2682) o <0.1A Low-Power Shutdown Mode o Ultra-Small Surface-Mount Packaging
General Description
The MAX2680/MAX2681/MAX2682 miniature, low-cost, low-noise downconverter mixers are designed for lowvoltage operation and are ideal for use in portable communications equipment. Signals at the RF input port are mixed with signals at the local oscillator (LO) port using a double-balanced mixer. These downconverter mixers operate with RF input frequencies between 400MHz and 2500MHz, and downconvert to IF output frequencies between 10MHz and 500MHz. The MAX2680/MAX2681/MAX2682 operate from a single +2.7V to +5.5V supply, allowing them to be powered directly from a 3-cell NiCd or a 1-cell Lithium battery. These devices offer a wide range of supply currents and input intercept (IIP3) levels to optimize system performance. Additionally, each device features a low-power shutdown mode in which it typically draws less than 0.1A of supply current. Consult the Selector Guide for various combinations of IIP3 and supply current. The MAX2680/MAX2681/MAX2682 are manufactured on a high-frequency, low-noise, advanced silicon-germanium process and are offered in the space-saving 6-pin SOT23 package.
MAX2680/MAX2681/MAX2682
Ordering Information
PART MAX2680EUT-T MAX2681EUT-T MAX2682EUT-T TEMP. RANGE -40C to +85C -40C to +85C -40C to +85C PINSOT PACKAGE TOP MARK 6 SOT23-6 6 SOT23-6 6 SOT23-6 AAAR AAAS AAAT
Applications
400MHz/900MHz/2.4GHz ISM-Band Radios Personal Communications Systems (PCS) Cellular and Cordless Phones Wireless Local Loop IEEE-802.11 and Wireless Data
GND 2
Pin Configuration
TOP VIEW
LO 1 6 SHDN
MAX2680 MAX2681 MAX2682
5
VCC
RFIN 3
4
IFOUT
Typical Operating Circuit appears at end of data sheet.
SOT23-6
Selector Guide
FREQUENCY PART ICC (mA) 900MHz IIP3 (dBm) -12.9 -6.1 -1.8 NF (dB) 6.3 7.0 6.5 GAIN (dB) 11.6 14.2 14.7 IIP3 (dBm) -8.2 +0.5 +4.4 1950MHz NF (dB) 8.3 11.1 10.2 GAIN (dB) 7.6 8.4 10.4 IIP3 (dBm) -6.9 +1.0 +3.2 2450MHz NF (dB) 11.7 12.7 13.4 GAIN (dB) 7.0 7.7 7.9 1
MAX2680 MAX2681 MAX2682
5.0 8.7 15.0
________________________________________________________________ Maxim Integrated Products
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 1-800-835-8769.
400MHz to 2.5GHz, Low-Noise, SiGe Downconverter Mixers MAX2680/MAX2681/MAX2682
ABSOLUTE MAXIMUM RATINGS
VCC to GND ..........................................................-0.3V to +6.0V RFIN Input Power (50 Source).....................................+10dBm LO Input Power (50 Source) ........................................+10dBm SHDN, IFOUT, RFIN to GND ......................-0.3V to (VCC + 0.3V) LO to GND..........................................(VCC - 1V) to (VCC + 0.3V) Continuous Power Dissipation (TA = +70C) SOT23-6 (derate 8.7mW/C above +70C)..................696mW Operating Temperature Range ..........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +160C Lead Temperature (soldering, 10sec) .............................+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 = +2.7V to +5.5V, SHDN = +2V, TA = TMIN to TMAX unless otherwise noted. Typical values are at VCC = +3V and TA = +25C. Minimum and maximum values are guaranteed over temperature by design and characterization.) PARAMETER Operating Supply Current Shutdown Supply Current Shutdown Input Voltage High Shutdown Input Voltage Low Shutdown Input Bias Current SYMBOL MAX2680 ICC ICC VIH VIL ISHDN 0 < SHDN < VCC 0.2 MAX2681 MAX2682 SHDN = 0.5V 2.0 0.5 CONDITIONS MIN TYP 5.0 8.7 15.0 0.05 MAX 7.7 12.7 21.8 5 A V V A mA UNITS
AC ELECTRICAL CHARACTERISTICS
(MAX2680/1/2 EV Kit, VCC = SHDN = +3.0V, TA = +25C, unless otherwise noted. RFIN and IFOUT matched to 50. PLO = -5dBm, PRFIN = -25dBm.) PARAMETER MAX2680 RF Frequency Range LO Frequency Range IF Frequency Range (Notes 1, 2) (Notes 1, 2) (Notes 1, 2) fRF = 400MHz, fLO = 445MHz, fIF = 45MHz Conversion Power Gain fRF = 900MHz, fLO = 970MHz, fIF = 70MHz fRF = 1950MHz, fLO = 1880MHz, fIF = 70MHz (Note 1) fRF = 2450MHz, fLO = 2210MHz, fIF = 240MHz Gain Variation Over Temperature Input Third-Order Intercept Point (Note 3) fRF = 1950MHz, fLO = 1880MHz, fIF = 70MHz, TA = TMIN to TMAX (Note 1) fRF = 900MHz, 901MHz, fLO = 970MHz, fIF = 70MHz fRF = 1950MHz, 1951MHz, fLO = 1880MHz, fIF = 70MHz fRF = 2450MHz, 2451MHz, fLO = 2210MHz, fIF = 240MHz fRF = 900MHz, fLO = 970MHz, fIF = 70MHz Noise Figure (Single Sideband) LO Input VSWR LO Leakage at IFOUT Port LO Leakage at RFIN Port IF/2 Spurious Response 2 fRF = 1950MHz, fLO = 2020MHz, fIF = 70MHz fRF = 2450MHz, fLO = 2210MHz, fIF = 240MHz 50 source impedance fLO = 1880MHz fLO = 1880MHz fRF = 1915MHz, fLO = 1880MHz, fIF = 70MHz (Note 4) 5.7 400 400 10 7.3 11.6 7.6 7.0 1.9 -12.9 -8.2 -6.9 6.3 8.3 11.7 1.5:1 -22 -26 -51 dBm dBm dBm dB dBm 2.4 dB 8.6 dB 2500 2500 500 MHz MHz MHz CONDITIONS MIN TYP MAX UNITS
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400MHz to 2.5GHz, Low-Noise, SiGe Downconverter Mixers
AC ELECTRICAL CHARACTERISTICS (continued)
(MAX2680/1/2 EV Kit, VCC = SHDN = +3.0V, TA = +25C, unless otherwise noted. RFIN and IFOUT matched to 50. PLO = -5dBm, PRFIN = -25dBm.) PARAMETER MAX2681 RF Frequency Range LO Frequency Range IF Frequency Range (Notes 1, 2) (Notes 1, 2) (Notes 1, 2) fRF = 400MHz, fLO = 445MHz, fIF = 45MHz Conversion Power Gain fRF = 900MHz, fLO = 970MHz, fIF = 70MHz fRF = 1950MHz, fLO = 1880MHz, fIF = 70MHz (Note 1) fRF = 2450MHz, fLO = 2210MHz, fIF = 240MHz Gain Variation Over Temperature Input Third-Order Intercept Point (Note 3) fRF = 1950MHz, fLO = 1880MHz, fIF = 70MHz, TA = TMIN to TMAX (Note 1) fRF = 900MHz, 901MHz, fLO = 970MHz, fIF = 70MHz fRF = 1950MHz, 1951MHz, fLO = 1880MHz, fIF = 70MHz fRF = 2450MHz, 2451MHz, fLO = 2210MHz, fIF = 240MHz fRF = 900MHz, fLO = 970MHz, fIF = 70MHz Noise Figure (Single Sideband) LO Input VSWR LO Leakage at IFOUT Port LO Leakage at RFIN Port IF/2 Spurious Response MAX2682 RF Frequency Range LO Frequency Range IF Frequency Range (Notes 1, 2) (Notes 1, 2) (Notes 1, 2) fRF = 400MHz, fLO = 445MHz, fIF = 45MHz Conversion Power Gain fRF = 900MHz, fLO = 970MHz, fIF = 70MHz fRF = 1950MHz, fLO = 1880MHz, fIF = 70MHz (Note 1) fRF = 2450MHz, fLO = 2210MHz, fIF = 240MHz Gain Variation Over Temperature Input Third-Order Intercept Point (Note 3) fRF = 1950MHz, fLO = 1880MHz, fIF = 70MHz, TA = TMIN to TMAX (Note 1) fRF = 900MHz, 901MHz, fLO = 970MHz, fIF = 70MHz fRF = 1950MHz, 1951MHz, fLO = 1880MHz, fIF = 70MHz fRF = 2450MHz, 2451MHz, fLO = 2210MHz, fIF = 240MHz fRF = 900MHz, fLO = 970MHz, fIF = 70MHz Noise Figure (Single Sideband) fRF = 1950MHz, fLO = 2020MHz, fIF = 70MHz fRF = 2450MHz, fLO = 2210MHz, fIF = 240MHz 8.7 400 400 10 13.4 14.7 10.4 7.9 2.1 -1.8 +4.4 +3.2 6.5 10.2 13.4 dB dBm 3.2 dB 11.7 dB 2500 2500 500 MHz MHz MHz fRF = 1950MHz, fLO = 2020MHz, fIF = 70MHz fRF = 2450MHz, fLO = 2210MHz, fIF = 240MHz 50 source impedance fLO = 1880MHz fLO = 1880MHz fRF = 1915MHz, fLO = 1880MHz, fIF = 70MHz (Note 4) 6.7 400 400 10 11.0 14.2 8.4 7.7 1.7 -6.1 +0.5 +1.0 7.0 11.1 12.7 1.5:1 -23 -27 -65 dBm dBm dBm dB dBm 2.3 dB 9.4 dB 2500 2500 500 MHz MHz MHz CONDITIONS MIN TYP MAX UNITS
MAX2680/MAX2681/MAX2682
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3
400MHz to 2.5GHz, Low-Noise, SiGe Downconverter Mixers MAX2680/MAX2681/MAX2682
AC ELECTRICAL CHARACTERISTICS (continued)
(MAX2680/1/2 EV Kit, VCC = SHDN = +3.0V, TA = +25C, unless otherwise noted. RFIN and IFOUT matched to 50. PLO = -5dBm, PRFIN = -25dBm.) PARAMETER LO Input VSWR LO Leakage at IFOUT Port LO Leakage at RFIN Port IF/2 Spurious Response Note 1: Note 2: Note 3: Note 4: fLO = 1880MHz fLO = 1880MHz fRF = 1915MHz, fLO = 1880MHz, fIF = 70MHz (Note 4) CONDITIONS 50 source impedance MIN TYP 1.5:1 -23 -27 -61 dBm dBm dBm MAX UNITS
Guaranteed by design and characterization. Operation outside of this specification is possible, but performance is not characterized and is not guaranteed. Two input tones at -25dBm per tone. This spurious response is caused by a higher-order mixing product (2x2). Specified RF frequency is applied and IF output power is observed at the desired IF frequency (70MHz).
Typical Operating Characteristics
(Typical Operating Circuit, VCC = SHDN = +3.0V, PRFIN = -25dBm, PLO = -5dBm, TA = +25C, unless otherwise noted.)
MAX2680 SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX2680/1/2-01
MAX2681 SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX2680/1/2-02
MAX2682 SUPPLY CURRENT vs. SUPPLY VOLTAGE
17 16 SUPPLY CURRENT (mA) 15 14 13 12 11 10 9 TA = +25C TA = -40C TA = +85C SHDN = VCC
MAX2680/1/2-03
7 SHDN = VCC 6 SUPPLY CURRENT (mA) TA = +85C 5 TA = +25C
10 SHDN = VCC 9 SUPPLY CURRENT (mA) TA = +85C
18
8 TA = +25C 7 TA = -40C
4
TA = -40C
3
6
2 2.5 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V)
5 2.5 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V)
8 2.5 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V)
4
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400MHz to 2.5GHz, Low-Noise, SiGe Downconverter Mixers
Typical Operating Characteristics (continued)
(Typical Operating Circuit, VCC = SHDN = +3.0V, PRFIN = -25dBm, PLO = -5dBm, TA = +25C, unless otherwise noted.)
MAX2680 SHUTDOWN SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX2680/1/2-04
MAX2680/MAX2681/MAX2682
MAX2681 SHUTDOWN SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX2680/1/2-05
MAX2682 SHUTDOWN SUPPLY CURRENT vs. SUPPLY VOLTAGE
SHUTDOWN SUPPLY CURRENT (A) 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 TA = -40C TA = +25C TA = +85C SHDN = GND
MAX2680/1/2-06
0.10 SHUTDOWN SUPPLY CURRENT (A) 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 2.5 3.0 3.5 4.0 4.5 5.0 TA = -40C TA = +25C TA = +85C SHDN = GND
0.10 SHUTDOWN SUPPLY CURRENT (A) 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 TA = -40C TA = +25C TA = +85C SHDN = GND
0.10
5.5
2.5
3.0
3.5
4.0
4.5
5.0
5.5
2.5
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
MAX2680 CONVERSION POWER GAIN vs. LO POWER
MAX2680/1/2-07
MAX2681 CONVERSION POWER GAIN vs. LO POWER
MAX2680/1/2-08
MAX2682 CONVERSION POWER GAIN vs. LO POWER
14 CONVERSION POWER GAIN (dB) 12 10 8 fRF = 2450MHz 6 4 2 0 fRF fIF fLO 900MHz 970MHz 70MHz 1950MHz 1880MHz 70MHz 2450MHz 2210MHz 240MHz -14 -12 -10 -8 -6 -4 -2 0 fRF = 900MHz fRF = 1950MHz
MAX2680/1/2-09
15 13 CONVERSION POWER GAIN (dB) 11 fRF = 1950MHz 9 7 5 3 1 -1 -14 -12 -10 -8 -6 -4 -2 0 LO POWER (dBm) fRF fLO fIF 900MHz 970MHz 70MHz 1950MHz 1880MHz 70MHz 2450MHz 2210MHz 240MHz fRF = 2450MHz fRF = 900MHz
16 14 CONVERSION POWER GAIN (dB) 12 10 8 6 4 2 0 -14 -12 -10 -8 -6 -4 -2 0 LO POWER (dBm) fRF = 2450MHz fRF fIF fLO 900MHz 970MHz 70MHz 1950MHz 1880MHz 70MHz 2450MHz 2210MHz 240MHz fRF = 1950MHz fRF = 900MHz
16
LO POWER (dBm)
MAX2680 CONVERSION POWER GAIN vs. TEMPERATURE
MAX2680/1/2-10
MAX2681 CONVERSION POWER GAIN vs. TEMPERATURE
MAX2680/1/2-11
MAX2682 CONVERSION POWER GAIN vs. TEMPERATURE
15 CONVERSION POWER GAIN (dB) 13 11 9 7 5 3 1 fRF = 2450MHz fRF = 1950MHz fRF = 900MHz
MAX2680/1/2-12
16 14 CONVERSION POWER GAIN (dB) 12 10 8 6 4 2 0 -40 -20 0 20 40 60 80 fRF = 2450MHz fRF fIF fLO 900MHz 970MHz 70MHz 1950MHz 1880MHz 70MHz 2450MHz 2210MHz 240MHz fRF = 1950MHz fRF = 900MHz
16 14 CONVERSION POWER GAIN (dB) 12 10 8 6 4 2 0 fRF = 2450MHz fRF = 1950MHz fRF = 900MHz
17
100
-40
-20
0
20
40
60
80
100
-40
-20
0
20
40
60
80
100
TEMPERATURE (C)
TEMPERATURE (C)
TEMPERATURE (C)
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5
400MHz to 2.5GHz, Low-Noise, SiGe Downconverter Mixers MAX2680/MAX2681/MAX2682
Typical Operating Characteristics (continued)
(Typical Operating Circuit, VCC = SHDN = +3.0V, PRFIN = -25dBm, PLO = -5dBm, TA = +25C, unless otherwise noted.)
MAX2680 INPUT IP3 vs. LO POWER
MAX2680/1/2-13
MAX2681 INPUT IP3 vs. LO POWER
MAX2680/1/2-14
MAX2682 INPUT IP3 vs. LO POWER
fRF = 1950MHz, 1951MHz fLO = 1880MHz fIF = 70MHz PRFIN = -25dBm PER TONE
MAX2680/1/2-15
-5 fRF = 1950MHz, 1951MHz fLO = 1880MHz fIF = 70MHz PRFIN = -25dBm PER TONE
2
7 6 5
-6 INPUT IP3 (dBm)
1 INPUT IP3 (dBm)
-7
0
INPUT IP3 (dBm) fRF = 1950MHz, 1951MHz fLO = 1880MHz fIF = 70MHz PRFIN = -25dBm PER TONE -14 -12 -10 -8 -6 -4 -2 0
4 3 2 1 0 -14 -12 -10 -8 -6 -4 -2 0
-8
-1
-9
-2
-10 -14 -12 -10 -8 -6 -4 -2 0 LO POWER (dBm)
-3 LO POWER (dBm)
LO POWER (dBm)
MAX2680 NOISE FIGURE vs. LO POWER
MAX2680/1/2-16
MAX2681 NOISE FIGURE vs. LO POWER
MAX2680/1/2-17
MAX2682 NOISE FIGURE vs. LO POWER
fRF fIF fLO 900MHz 970MHz 70MHz 1950MHz 2020MHz 70MHz 2450MHz 2210MHz 70MHz fRF = 2450MHz fRF = 1950MHz fRF = 900MHz 5
MAX2680/1/2-18
16 14 12 NOISE FIGURE (dB) 10 8 6 4 2 0 -14 -12 -10 -8 -6 -4 -2 0 LO POWER (dBm) fRF = 900MHz fRF fLO fIF 900MHz 970MHz 70MHz 1950MHz 2020MHz 70MHz 2450MHz 2210MHz 70MHz fRF = 2450MHz fRF = 1950MHz
20 18 16 NOISE FIGURE (dB) 14 12 10 8 6 4 2 0 -14 -12 -10 -8 -6 -4 -2 0 LO POWER (dBm) fRF fIF fLO 900MHz 970MHz 70MHz 1950MHz 2020MHz 70MHz 2450MHz 2210MHz 70MHz fRF = 900MHz fRF = 2450MHz fRF = 1950MHz
25
20 NOISE FIGURE (dB)
15
10
0 -14 -12 -10 -8 -6 -4 -2 0 LO POWER (dBm)
MAX2680 RF PORT IMPEDANCE vs. RF FREQUENCY
300 250 REAL IMPEDANCE () 200 150 100 50 0 0 500 1000 1500 2000 RF FREQUENCY (MHz) REAL
MAX2680/1/2-19
MAX2681 RF PORT IMPEDANCE vs. RF FREQUENCY
0 -100 -200 -300 -400 -500 300 250 REAL IMPEDANCE () 200 150 100 50 0 0 500 1000 1500 2000 RF FREQUENCY (MHz) REAL IMAGINARY
MAX2680/1/2-20
MAX2682 RF PORT IMPEDANCE vs. RF FREQUENCY
0 -100 -200 -300 -400 -500 300 250 REAL IMPEDANCE () 200 150 100 50 0 0 500 1000 1500 2000 RF FREQUENCY (MHz) fLO = 970MHz PLO = -5dBm REAL IMAGINARY
MAX2680/1/2-21
0 -100 -200 -300 -400 -500
IMAGINARY IMAGINARY IMPEDANCE () IMAGINARY IMPEDANCE () IMAGINARY IMPEDANCE ()
fLO = 970MHz PLO = -5dBm
-600 2500
fLO = 970MHz PLO = -5dBm
-600 2500
-600 2500
6
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400MHz to 2.5GHz, Low-Noise, SiGe Downconverter Mixers
Typical Operating Characteristics (continued)
(Typical Operating Circuit, VCC = SHDN = +3.0V, PRFIN = -25dBm, PLO = -5dBm, TA = +25C, unless otherwise noted.)
MAX2680/MAX2681/MAX2682
MAX2680 IF PORT IMPEDANCE vs. IF FREQUENCY
1200 1000 REAL IMPEDANCE () 800 600 400 200 0 0 100 200 300 400 500 IF FREQUENCY (MHz) REAL
MAX2680/1/2-22
MAX2681 IF PORT IMPEDANCE vs. IF FREQUENCY
0 -100 -200 -300 -400 -500 -600 1200 1000 800 600 400 200 0 0 100 200 300 400 500 IF FREQUENCY (MHz) REAL
MAX2680/1/2-23
MAX2682 IF PORT IMPEDANCE vs. IF FREQUENCY
0 -100 -200 -300 -400 -500 -600 800 700 IMAGINARY IMPEDANCE () REAL IMPEDANCE () 600 500 400 300 200 100 0 0 100 200 300 400 500 IF FREQUENCY (MHz) REAL IMAGINARY -200 -250 -300 -350 -400
MAX2680/1/2-24 0 fLO = 970MHz PLO = -5dBm -50
fLO = 970MHz PLO = -5dBm
fLO = 970MHz PLO = -5dBm IMAGINARY IMPEDANCE () REAL IMPEDANCE ()
-100 -150
IMAGINARY
IMAGINARY
MAX2680 LO PORT RETURN LOSS
MAX2680/1/2-25
MAX2681 LO PORT RETURN LOSS
MAX2680/1/2-26
MAX2682 LO PORT RETURN LOSS
+5 0 RETURN LOSS (dB) -5 -10 -15 -20 -25 -30 -35 -40
MAX2680/1/2-27
+10 +5 0 RETURN LOSS (dB) -5 -10 -15 -20 -25 -30 -35 -40 200 760 1320 1880 2440
+10 +5 0 RETURN LOSS (dB) -5 -10 -15 -20 -25 -30 -35 -40
+10
3000
200
760
1320
1880
2440
3000
200
760
1320
1880
2440
3000
FREQUENCY (MHz)
FREQUENCY (MHz)
FREQUENCY (MHz)
MAX2680 LO-to-IF AND LO-to-RF ISOLATION
MAX2680/1/2-28
MAX2681 LO-to-IF AND LO-to-RF ISOLATION
35 30 ISOLATION (dB) 25 20 15 10 5 0 10 0 500 1000 1500 2000 2500 0 LO-to-RF ISOLATION ISOLATION (dB) 25 LO-to-IF ISOLATION
MAX2680/1/2-29
MAX2682 LO-to-IF AND LO-to-RF ISOLATION
MAX2680/1/2-30
35 30 25 ISOLATION (dB) 20 15 10 5 0 0 500 1000 1500 2000 LO-to-RF ISOLATION LO-to-IF ISOLATION
40
35 LO-to-IF ISOLATION
30
20
LO-to-RF ISOLATION
15
2500
500
1000
1500
2000
2500
LO FREQUENCY (MHz)
LO FREQUENCY (MHz)
LO FREQUENCY (MHz)
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7
IMAGINARY IMPEDANCE ()
400MHz to 2.5GHz, Low-Noise, SiGe Downconverter Mixers MAX2680/MAX2681/MAX2682
Typical Operating Characteristics (continued)
(Typical Operating Circuit, VCC = SHDN = +3.0V, PRFIN = -25dBm, PLO = -5dBm, TA = +25C, unless otherwise noted.)
MAX2680 TURN-OFF/ON CHARACTERISTICS
MAX2680/1/2-31
MAX2681 TURN-OFF/ON CHARACTERISTICS
MAX2680/1/2-32
MAX2682 TURN-OFF/ON CHARACTERISTICS
SHDN 2V/div
MAX2680/1/2-33
SHDN 2V/div
SHDN 2V/div
IFOUT 50mV/ div
IFOUT 50mV/ div
IFOUT 50mV/ div
Z1 = 39pF 500ns/div
Z1 = 39pF 500ns/div
Z2 = 39pF 500ns/div
Pin Description
PIN 1 2 3 4 5 6 NAME LO GND RFIN IFOUT VCC SHDN FUNCTION Local-Oscillator Input. Apply a local-oscillator signal with an amplitude of -10dBm to 0 (50 source). ACcouple this pin to the oscillator with a DC-blocking capacitor. Nominal DC voltage is VCC - 0.4V. Mixer Ground. Connect to the ground plane with a low-inductance connection. Radio Frequency Input. AC-couple to this pin with a DC-blocking capacitor. Nominal DC voltage is 1.5V. See Applications Information section for details on impedance matching. Intermediate Frequency Output. Open-collector output requires an inductor to VCC. AC-couple to this pin with a DC-blocking capacitor. See Applications Information section for details on impedance matching. Supply Voltage Input, +2.7V to +5.5V. Bypass with a capacitor to the ground plane. Capacitor value depends upon desired operating frequency. Active-Low Shutdown. Drive low to disable all device functions and reduce the supply current to less than 5A. For normal operation, drive high or connect to VCC.
8
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400MHz to 2.5GHz, Low-Noise, SiGe Downconverter Mixers
Detailed Description
The MAX2680/MAX2681/MAX2682 are 400MHz to 2.5GHz, silicon-germanium, double-balanced downconverter mixers. They are designed to provide optimum linearity performance for a specified supply current. They consist of a double-balanced Gilbert-cell mixer with single-ended RF, LO, and IF port connections. An on-chip bias cell provides a low-power shutdown feature. Consult the Selector Guide for device features and comparison.
IF Output
The IF output frequency range extends from 10MHz to 500MHz. IFOUT is a high-impedance, open-collector output that requires an external inductor to VCC for proper biasing. For optimum performance, the IF port requires an impedance-matching network. The configuration and values for the matching network is dependent upon the frequency and desired output impedance. For assistance in choosing components for optimal performance, refer to Tables 3 and 4 as well as the IF Port Impedance vs. IF Frequency graph in the Typical Operating Characteristics.
MAX2680/MAX2681/MAX2682
Applications Information
Local-Oscillator (LO) Input
The LO input is a single-ended broadband port with a typical input VSWR of better than 2.0:1 from 400MHz to 2.5GHz. The LO signal is mixed with the RF input signal, and the resulting downconverted output appears at IFOUT. AC-couple LO with a capacitor. Drive the LO port with a signal ranging from -10dBm to 0 (50 source).
Power-Supply and SHDN Bypassing
Proper attention to voltage supply bypassing is essential for high-frequency RF circuit stability. Bypass VCC with a 10F capacitor in parallel with a 1000pF capacitor. Use separate vias to the ground plane for each of the bypass capacitors and minimize trace length to reduce inductance. Use separate vias to the ground plane for each ground pin. Use low-inductance ground connections. Decouple SHDN with a 1000pF capacitor to ground to minimize noise on the internal bias cell. Use a series resistor (typically 100) to reduce coupling of high-frequency signals into the SHDN pin.
RF Input
The RF input frequency range is 400MHz to 2.5GHz. The RF input requires an impedance-matching network as well as a DC-blocking capacitor that can be part of the matching network. Consult Tables 1 and 2, as well as the RF Port Impedance vs. RF Frequency graph in the Typical Operating Characteristics for information on matching.
Layout Issues
A well designed PC board is an essential part of an RF circuit. For best performance, pay attention to powersupply issues as well as to the layout of the RFIN and IFOUT impedance-matching network.
Table 1. RFIN Port Impedance
FREQUENCY PART 400MHz MAX2680 MAX2681 MAX2682 179-j356 209-j332 206-j306 900MHz 54-j179 75-j188 78-j182 1950MHz 32-j94 34-j108 34-j106 2450MHz 33-j73 33-j86 29-j86
Table 2. RF Input Impedance-Matching Component Values
FREQUENCY MATCHING COMPONENTS Z1 Z2 Z3 MAX2680 400 MHz 86nH 270pF Open 900 MHz 270pF 22nH Open 1950 MHz 1.5pF 270pF 1.8nH 2450 MHz Short 270pF 1.8nH 400 MHz 68nH 270pF 0.5pF MAX2681 900 MHz 270pF 18nH Open 1950 MHz 1.5pF 270pF 1.8nH 2450 MHz Short 270pF 2.2nH 400 MHz 68nH 270pF 0.5pF MAX2682 900 MHz 1.5pF 270pF 10nH 1950 MHz Short 270pF 2.2nH 2450 MHz Short 270pF 1.2nH
Note: Z1, Z2, and Z3 are found in the Typical Operating Circuit.
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400MHz to 2.5GHz, Low-Noise, SiGe Downconverter Mixers MAX2680/MAX2681/MAX2682
Table 3. IFOUT Port Impedance
FREQUENCY PART 45MHz MAX2680 MAX2681 MAX2682 960-j372 934-j373 670-j216 70MHz 803-j785 746-j526 578-j299 240MHz 186-j397 161-j375 175-j296
Power-Supply Layout
To minimize coupling between different sections of the IC, the ideal power-supply layout is a star configuration with a large decoupling capacitor at a central V CC node. The V CC traces branch out from this central node, each going to a separate VCC node on the PC board. At the end of each trace is a bypass capacitor that has low ESR at the RF frequency of operation. This arrangement provides local decoupling at the VCC pin. At high frequencies, any signal leaking out of one supply pin sees a relatively high impedance (formed by the VCC trace inductance) to the central VCC node, and an even higher impedance to any other supply pin, as well as a low impedance to ground through the bypass capacitor.
Table 4. IF Output Impedance-Matching Components
MATCHING COMPONENT L1 C2 R1 FREQUENCY 45MHz 390nH 39pF 250 70MHz 330nH 15pF Open 240MHz 82nH 3pF Open
Impedance-Matching Network Layout
The RFIN and IFOUT impedance-matching networks are very sensitive to layout-related parasitics. To minimize parasitic inductance, keep all traces short and place components as close as possible to the chip. To minimize parasitic capacitance, use cutouts in the ground plane (and any other plane) below the matching network components. However, avoid cutouts that are larger than necessary since they act as aperture antennas.
Typical Operating Circuit
C1 LO INPUT 1 LO SHDN 6 C3 SHUTDOWN CONTROL
2
GND
MAX2680 MAX2681 MAX2682
VCC
5 C4 1000pF C5 10F
VCC +2.7V TO +5.5V L1 R1
RF INPUT
Z1
Z2
3
RFIN
IFOUT
4 C2
IF OUTPUT
Z3
THE VALUES OF MATCHING COMPONENTS C2, L1, R1, Z1, Z2, AND Z3 DEPEND ON THE IF AND RF FREQUENCY AND DOWNCONVERTER. SEE TABLES 2 AND 4.
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400MHz to 2.5GHz, Low-Noise, SiGe Downconverter Mixers
Package Information
6LSOT.EPS
MAX2680/MAX2681/MAX2682
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400MHz to 2.5GHz, Low-Noise, SiGe Downconverter Mixers MAX2680/MAX2681/MAX2682
NOTES
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