Active Receive Mixer LF to 500 MHz AD8342 Broadband RF port: LF to 500 MHz Conversion gain: 3.7 dB Noise figure: 12.2 dB Input IP3: 22.7 dBm Input P1dB: 8.3 dBm LO drive: 0 dBm Differential high impedance RF input port Single-ended, 50 Ω LO input port Single-supply operation: 5 V @ 98 mA Power-down mode Exposed paddle LFCSP: 3 mm × 3 mm FUNCTIONAL BLOCK DIAGRAM VPDC PWDN 12 11 COMM 13 EXRB COMM 10 9 8 COMM 7 IFOP RFIN 15 6 IFOM VPMX 16 5 COMM BIAS RFCM 14 AD8342 1 2 3 4 VPLO LOCM LOIN COMM 05352-001 FEATURES Figure 1. APPLICATIONS Cellular base station receivers ISM receivers Radio links RF instrumentation GENERAL DESCRIPTION The AD8342 is a high performance, broadband active mixer. It is well suited for demanding receive-channel applications that require wide bandwidth on all ports and very low intermodulation distortion and noise figure. The AD8342 provides a typical conversion gain of 3.7 dB with an RF frequency of 238 MHz. The integrated LO driver presents a 50 Ω input impedance with a low LO drive level, helping to minimize the external component count. The differential high impedance broadband RF port allows for easy interfacing to both active devices and passive filters. The RF input accepts input signals as large as 1.6 V p-p or 8 dBm (relative to 50 Ω) at P1dB. The open-collector differential outputs provide excellent balance and can be used with a differential filter or IF amplifier, such as the AD8369 or AD8351. These outputs can also be converted to a single-ended signal through the use of a matching network or a transformer (balun). When centered on the VPOS supply voltage, the outputs may swing ±2 V differentially. The AD8342 is fabricated on an Analog Devices proprietary, high performance SiGe IC process. The AD8342 is available in a 16-lead LFCSP. It operates over a −40°C to +85°C temperature range. An evaluation board is also available. Rev. 0 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 © 2005 Analog Devices, Inc. All rights reserved. AD8342 TABLE OF CONTENTS Specifications..................................................................................... 3 AC Interfaces................................................................................... 15 AC Performance ............................................................................... 4 IF Port .......................................................................................... 16 Spur Table .......................................................................................... 5 LO Considerations ..................................................................... 17 Absolute Maximum Ratings............................................................ 6 High IF Applications.................................................................. 18 ESD Caution.................................................................................. 6 Evaluation Board ............................................................................ 19 Pin Configuration and Function Descriptions............................. 7 Outline Dimensions ....................................................................... 20 Typical Performance Characteristics ............................................. 8 Ordering Guide .......................................................................... 20 Circuit Description......................................................................... 14 REVISION HISTORY 4/05—Revision 0: Initial Version Rev. 0 | Page 2 of 20 AD8342 SPECIFICATIONS VS = 5 V, TA = 25°C, fRF = 238 MHz, fLO = 286 MHz, LO power = 0 dBm, ZO = 50 Ω, RBIAS = 1.82 kΩ, RF termination = 100 Ω, IF terminated into 100 Ω through a 2:1 ratio balun, unless otherwise noted. Table 1. Parameter RF INPUT INTERFACE Return Loss Input Impedance DC Bias Level OUTPUT INTERFACE Output Impedance DC Bias Voltage Power Range LO INTERFACE Return Loss DC Bias Voltage POWER-DOWN INTERFACE PWDN Threshold PWDN Response Time PWDN Input Bias Current POWER SUPPLY Positive Supply Voltage Quiescent Current VPDC VPMX, IFOP, IFOM VPLO Total Quiescent Current Power-Down Current Conditions Min Hi-Z input terminated with 100 Ω off-chip resistor Frequency = 238 MHz (measured at RFIN with RFCM acgrounded) Internally generated; port must be ac-coupled Differential impedance, frequency = 48 MHz Supplied externally Via a 2:1 impedance ratio transformer 4.75 Typ Max Unit 10 1||0.4 dB kΩ||pF 2.4 V 10||0.5 VS 5.25 13 kΩ||pF V dBm Internally generated; port must be ac-coupled 10 VS − 1.6 dB V Device enabled, IF output to 90% of its final level Device disabled, supply current <5 mA Device enabled Device disabled 3.5 0.4 4 −80 +100 V µs µs µA µA 4.75 Supply current for bias cells Supply current for mixer, RBIAS = 1.82 kΩ Supply current for LO limiting amplifier VS = 5 V Device disabled Rev. 0 | Page 3 of 20 85 5 5 58 35 98 500 5.25 113 V mA mA mA mA µA AD8342 AC PERFORMANCE VS = 5 V, TA = 25°C, LO power = 0 dBm, ZO = 50 Ω, RBIAS = 1.82 kΩ, RF termination 100 Ω, IF terminated into 100 Ω via a 2:1 ratio balun, unless otherwise noted. Table 2. Parameter RF FREQUENCY RANGE1 LO FREQUENCY RANGE1 IF FREQUENCY RANGE1 CONVERSION GAIN SSB NOISE FIGURE INPUT THIRD-ORDER INTERCEPT INPUT SECOND-ORDER INTERCEPT INPUT 1 dB COMPRESSION POINT LO TO IF OUTPUT LEAKAGE LO TO RF INPUT LEAKAGE 2× LO TO IF OUTPUT LEAKAGE RF TO IF OUTPUT LEAKAGE IF/2 SPURIOUS 1 Conditions Min 50 60 10 High side LO fRF = 460 MHz, fLO = 550 MHz, fIF = 90 MHz fRF = 238 MHz, fLO = 286 MHz, fIF = 48 MHz fRF = 460 MHz, fLO = 550 MHz, fIF = 90 MHz fRF = 238 MHz, fLO = 286 MHz, fIF = 48 MHz fRF1 = 460 MHz, fRF2 = 461 MHz, fLO = 550 MHz, fIF1 = 90 MHz, fIF2 = 89 MHz each RF tone −10 dBm fRF1 = 238 MHz, fRF2 = 239 MHz, fLO = 286MHz, fIF1 = 48MHz, fIF2 = 47MHz each RF tone −10 dBm fRF1 = 460 MHz, fRF2 = 410 MHz, fLO = 550 MHz, fIF1 = 90 MHz, fIF2 = 140 MHz fRF1 = 238 MHz, fRF2 = 188 MHz, fLO = 286 MHz, fIF1 = 48MHz, fIF2 = 98 MHz fRF = 460 MHz, fLO = 550 MHz, fIF = 90 MHz fRF = 238 MHz, fLO = 286 MHz, fIF = 48 MHz LO power = 0 dBm, fLO = 286 MHz LO power = 0 dBm, fLO = 286 MHz LO power = 0 dBm, fRF = 238 MHz, fLO = 286 MHz IF terminated into 100 Ω and measured with a differential probe RF power = −10 dBm, fRF = 238 MHz, fLO = 286 MHz RF power = −10 dBm, fRF = 238 MHz, fLO = 286 MHz Typ Max 500 850 350 3.2 3.7 12.5 12.2 22.2 Unit MHz MHz MHz dB dB dB dB dBm 22.7 dBm 50 dBm 44 dBm 8.5 8.3 −27 −55 −47 dBm dBm dBc dBc dBm −32 −70 dBc dBc Frequency ranges are those that were extensively characterized; this device can operate over a wider range. See the High IF Applications section for details. Rev. 0 | Page 4 of 20 AD8342 SPUR TABLE VS = 5 V, TA = 25°C, RF and LO power = 0 dBm, fRF = 238MHz, fLO = 286MHz, ZO = 50 Ω, RBIAS = 1.82 kΩ, RF termination 100 Ω, IF terminated into 100 Ω via a 2:1 ratio balun. Note: Measured using standard test board. Typical noise floor of measurement system = −100 dBm. Table 3. m n nfRF − mfLO 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 <−100 −39 −52 −81 −78 −98 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 −25 3.5 −47 −57 −70 −79 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 −54 −42 −51 −79 −80 −95 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 −28 −6 −49 −61 −79 −87 −99 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 −45 −48 −54 −82 −80 −96 <−100 −96 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 −35 −16 −56 −61 −85 −94 −96 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 −39 −50 −56 −74 −87 −95 <−100 −98 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 −36 −28 −62 −69 −92 −88 <−100 <−100 <−100 <−100 <−100 −96 <−100 <−100 <−100 <−100 −42 −57 −62 −94 −93 −98 <−100 <−100 −97 <−100 <−100 <−100 −99 <−100 <−100 <−100 −57 −37 −66 −85 −96 −94 <−100 <−100 <−100 <−100 <−100 −97 <−100 −97 <−100 <−100 −44 −68 −71 −89 −95 <−100 <−100 <−100 <−100 <−100 −99 <−100 −98 <−100 −98 <−100 −42 −45 −80 −86 <−100 <−100 <−100 <−100 <−100 −99 <−100 −96 <−100 −97 −98 <−100 −41 −54 −80 −86 −97 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 −99 <−100 <−100 −46 −37 −67 −90 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 −59 −61 −79 −81 −95 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 <−100 Rev. 0 | Page 5 of 20 AD8342 ABSOLUTE MAXIMUM RATINGS Table 4. Parameter Supply Voltage, VS RF Input Level LO Input Level PWDN Pin IFOP, IFOM Bias Voltage Minimum Resistor from EXRB to COMM Internal Power Dissipation θJA Maximum Junction Temperature Operating Temperature Range Storage Temperature Range Rating 5.5 V 12 dBm 12 dBm VS + 0.5 V 5.5 V 1.8 kΩ 650 mW 77°C/W 135°C −40°C to +85°C −65°C to +150°C Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ESD CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. Rev. 0 | Page 6 of 20 AD8342 12 VPDC 11 PWDN 10 EXRB 05352-002 9 COMM COMM 8 14 RFCM IFOP 7 TOP VIEW (Not to Scale) COMM 5 COMM 4 AD8342 IFOM 6 LOIN 3 13 COMM PIN 1 INDICATOR VPLO 1 LOCM 2 15 RFIN 16 VPMX PIN CONFIGURATION AND FUNCTION DESCRIPTIONS Figure 2. 16-Lead LFCSP Table 5. Pin Function Descriptions Pin No. 1 2 3 Mnemonic VPLO LOCM LOIN 4, 5, 8, 9, 13 6, 7 10 COMM IFOM, IFOP EXRB 11 12 14 15 16 PWDN VPDC RFCM RFIN VPMX Function Positive Supply Voltage for the LO Buffer: 4.75 V to 5.25 V. AC Ground for Limiting LO Amplifier. Internally biased to Vs − 1.6 V. AC-couple to ground. LO Input. Nominal input level 0 dBm. Input level range −10 dBm to +4 dBm (relative to 50 Ω). Internally biased to Vs − 1.6 V. AC-couple. Device Common (DC Ground). Differential IF Outputs (Open Collectors). Each requires dc bias of 5.00 V (nominal). Mixer Bias Voltage. Connect resistor from EXRB to ground. Typical value of 1.82 kΩ sets mixer current to nominal value. Minimum resistor value from EXRB to ground = 1.8 kΩ. Internally biased to 1.17 V. Connect to Ground for Normal Operation. Connect pin to VS for disable mode. Positive Supply Voltage for the DC Bias Cell: 4.75 V to 5.25 V. AC Ground for RF Input. Internally biased to 2.4 V. AC-couple to ground. RF Input. Internally biased to 2.4 V. Must be ac-coupled. Positive Supply Voltage for the Mixer: 4.75 V to 5.25 V. Rev. 0 | Page 7 of 20 AD8342 TYPICAL PERFORMANCE CHARACTERISTICS VS = 5 V, TA = 25°C, RF power = −10 dBm, LO power = 0 dBm, ZO = 50 Ω, RBIAS = 1.82 kΩ, RF termination 100 Ω, IF terminated into 100 Ω via a 2:1 ratio balun, unless otherwise noted. 6 6 5 5 GAIN (dB) 3 RF = 238MHz 4 GAIN (dB) IF = 48MHz 4 RF = 460MHz 3 IF = 140MHz IF = 10MHz IF = 90MHz 05352-004 1 50 100 150 200 250 300 350 400 450 500 05352-005 2 2 1 10 550 50 100 150 200 250 300 RF FREQUENCY (MHz) IF FREQUENCY (MHz) Figure 3. Conversion Gain vs. RF Frequency Figure 6. Conversion Gain vs. IF Frequency 5 350 5.0 4.5 IF = 48MHz IF = 10MHz 4 4.0 3 IF = 140MHz GAIN (dB) GAIN (dB) 3.5 IF = 90MHz 2 3.0 2.5 2.0 1.5 1 0 –15 –10 –5 0 05352-026 05352-025 1.0 0.5 0 4.75 5 4.85 4.95 LO LEVEL (dBm) 4.5 45 4.0 40 3.5 35 3.0 2.5 2.0 25 20 15 1.0 10 0.5 20 40 60 NORMAL MEAN = 3.7 STD. DEV. = 0.06 CONVERSION GAIN (238MHz) PERCENTAGE 30 1.5 0 5.25 05352-054 PERCENTAGE 50 05352-039 GAIN (dB) 5.0 –20 5.15 Figure 7. Gain vs. Vpos, fRF = 238 MHz, fLO = 286 MHz Figure 4. Gain vs. LO Level, RF Frequency = 238 MHz 0 –40 5.05 VPOS (V) 5 0 3.40 80 3.45 3.50 3.55 3.60 3.65 3.70 3.75 3.80 3.85 3.90 CONVERSION GAIN (238MHz) TEMPERATURE (°C) Figure 8. Conversion Gain Distribution, fRF = 238 MHz, fLO = 286 MHz Figure 5. Gain vs. Temperature, fRF = 238 MHz, fLO = 286 MHz Rev. 0 | Page 8 of 20 AD8342 27 27 26 26 25 25 IF = 48MHz 24 IF = 90MHz IF = 10MHz INPUT IP3 (dBm) 23 22 21 IF = 140MHz 20 23 RF = 238MHz 21 20 18 17 50 100 150 200 250 300 350 400 450 18 17 10 550 500 50 100 150 300 Figure 9. Input IP3 vs. RF Frequency Figure 12. Input IP3 vs. IF Frequency 27 26 25 350 25 IF = 48MHz 24 IF = 10MHz INPUT IP3 (dBm) 24 23 22 21 140MHz IF = 90MHz 23 22 21 20 19 19 05352-027 20 18 –13 –11 –9 –7 –5 –3 –1 1 18 17 4.75 5 3 4.80 4.85 4.90 4.95 LO LEVEL (dBm) 26 18 25 16 24 14 23 22 21 5.20 5.25 8 4 05352-032 6 18 60 NORMAL MEAN = 22.7 STD. DEV. = 0.41 INPUT IP3 (238MHz) PERCENTAGE 10 19 40 5.15 12 20 20 5.10 05352-055 PERCENTAGE 20 0 5.05 Figure 13. Input IP3 vs. Vpos, fRF = 238 MHz, fRF2 = 239 MHz LO Frequency = 286 MHz 27 –20 5.00 VPOS (V) Figure 10. Input IP3 vs. LO Level, fRF1 = 238 MHz, fRF2 = 239 MHz INPUT IP3 (dBm) 250 IF FREQUENCY (MHz) 26 17 –40 200 RF FREQUENCY (MHz) 27 17 –15 05352-008 19 05352-007 19 INPUT IP3 (dBm) RF = 460MHz 22 05352-028 INPUT IP3 (dBm) 24 2 0 20.6 80 TEMPERATURE (°C) 21.0 21.4 21.8 22.2 22.6 23.0 23.4 23.8 24.2 INPUT IP3 (238MHz) Figure 14. Input IP3 Distribution, fRF = 238 MHz, fLO = 286 MHz Figure 11. Input IP3 vs. Temperature, fRF1 = 238 MHz, fRF2 = 239 MHz, fLO = 286 MHz Rev. 0 | Page 9 of 20 AD8342 13 10 12 9 11 8 9 8 48MHz 7 140MHz 6 7 INPUT P1dB (dBm) RF = 238MHz 6 5 4 3 5 4 100 150 200 250 300 350 400 450 500 1 0 550 10 300 350 9 IF = 10MHz IF = 90MHz 8 8.0 IF = 140MHz 7.5 7 INPUT P1dB (dBm) INPUT P1dB (dBm) 250 10 IF = 48MHz 7.0 6.5 6 5 4 3 6.0 05352-038 2 5.5 –13 –11 –9 –7 –5 –3 –1 1 1 0 4.75 5 3 4.85 LO LEVEL (dBm) 4.95 5.05 5.15 5.25 VPOS (V) Figure 19. Input P1dB vs. Vpos, fRF = 238 MHz, fLO = 286 MHz Figure 16. Input P1dB vs. LO Level, fRF = 238 MHz 28 10 26 9 24 22 7 20 PERCENTAGE 8 6 5 4 16 14 12 10 8 2 6 1 –20 0 20 40 60 NORMAL MEAN = 8.3 STD. DEV. = 0.07 IP1dB (238MHz) PERCENTAGE 18 3 4 05352-033 INPUT P1dB (dBm) 200 Figure 18. Input P1dB vs. IF Frequency 8.5 0 –40 150 Figure 15. Input P1dB vs. RF Frequency 9.5 5.0 –15 100 IF FREQUENCY (MHz) 10.0 9.0 50 RF FREQUENCY (MHz) 05352-031 3 50 05352-014 05352-013 2 05352-056 INPUT P1dB (dBm) 10MHz 90MHz 10 RF = 460MHz 2 0 8.00 8.05 8.10 8.15 8.20 8.25 8.30 8.35 8.40 8.45 8.50 8.55 8.60 80 IP1dB (238MHz) TEMPERATURE (°C) Figure 20. Input IP3 Distribution, fRF = 238 MHz, fLO = 286 MHz Figure 17. Input P1dB vs. Temperature, fRF = 238 MHz, fLO = 286 MHz Rev. 0 | Page 10 of 20 AD8342 60 60 IF = 90MHz IF = 10MHz RF = 238MHz IF = 140MHz 50 40 INPUT IP2 (dBm) 40 IF = 48MHz 30 20 30 20 0 100 150 200 250 300 350 400 450 0 10 550 500 05352-011 10 05352-010 10 50 100 200 250 300 350 IF FREQUENCY (MHz) Figure 21. Input IP2 vs. RF Frequency (Second RF = R F - 50 MHz) Figure 24. Input IP2 vs. IF Frequency (Second RF = R F - 50 MHz) 60 60 58 58 IF = 10MHz 56 56 IF = 48MHz 54 INPUT IP2 (dBm) INPUT IP2 (dBm) 54 52 50 48 52 50 48 IF = 90MHz 46 46 IF = 140MHz 44 05352-029 44 42 40 –15 –13 –11 –9 –7 –5 –3 –1 1 3 42 40 4.75 5 4.85 LO LEVEL (dBm) 4.95 5.05 5.15 5.25 VPOS (V) Figure 25. Input IP2 vs. Vpos, fRF1 = 238 MHz, fRF2 = 188 MHz, fLO = 286 MHz Figure 22. Input IP2 vs. LO Level, fRF = 238 MHz, ,fRF2 =188MHz 14.0 16 RF = 460MHz 14 13.5 NOISE FIGURE (dB) 12 13.0 12.5 12.0 RF = 238MHz 10 8 6 4 11.5 100 150 200 250 300 350 400 450 500 0 10 550 05352-017 11.0 50 2 05352-016 NOISE FIGURE (dB) 150 RF FREQUENCY (MHz) 05352-030 INPUT IP2 (dBm) RF = 460MHz 50 60 110 160 210 260 RF FREQUENCY (MHz) IF FREQUENCY (MHz) Figure 23. Noise Figure vs. RF Frequency, IF Frequency = 48 MHz Figure 26. Noise Figure vs. IF Frequency Rev. 0 | Page 11 of 20 310 AD8342 16 30 15 25 20 PERCENTAGE 14 NF = 140MHz NF (dB) NORMAL MEAN = 12.25 STD. DEV. = 0.14 NF PERCENTAGE NF = 90MHz 13 15 12 10 NF = 10MHz NF = 48MHz 10 –15 –13 –11 –9 –7 –5 –3 –1 1 3 05352-023 5 05352-018 11 0 11.8 5 11.9 12.0 12.1 12.2 12.3 12.4 12.5 12.6 12.7 12.8 LO POWER (dBm) NOISE FIGURE (dB) Figure 27. Noise Figure vs. LO Power, fRF = 238 MHz Figure 30. Noise Figure Distribution, fRF = 238 MHz, fLO = 286 MHz 105 30 5.0 NOISE FIGURE AND INPUT IP3 (dBm) 4.5 3.0 2.5 2.0 1.5 05352-024 1.0 0.5 0 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 INPUT IP3 20 95 15 90 NOISE FIGURE 10 85 CURRENT 80 5 0 1.8 3.4 2.0 2.2 2.4 2.6 2.8 75 3.0 05352-015 GAIN (dB) 3.5 100 25 SUPPLY CURRENT (mA) 4.0 RBIAS (kΩ) RBIAS (kΩ) Figure 31. Noise Figure, Input IP3 and Supply Current vs. RBIAS, fRF1 = 238 MHz, fRF2 = 239 MHz, fLO = 286 MHz Figure 28. Gain vs. RBIAS, RF Frequency = 238 MHz, LO Frequency = 286MHz 10 61 9 59 8 INPUT P1dB (dBm) INPUT IP2 (dBm) 57 55 53 51 7 6 5 4 3 49 05352-037 45 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 05352-036 2 47 1 0 1.8 3.4 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 RBIAS (kΩ) RBIAS (kΩ) Figure 29. Input IP2 vs. RBIAS, fRF = 238 MHz (Second RF = RF – 50MHz), fLO = 286 MHz Rev. 0 | Page 12 of 20 Figure 32. Input P1dB vs. RBIAS, fRF = 238 MHz, fLO = 286 MHz AD8342 0 120 –10 100 SUPPLY CURRENT (mA) –20 LEAKAGE (dBc) –30 –40 –50 –60 80 60 40 –70 –90 50 250 450 650 05352-034 05352-021 20 –80 0 –40 850 –20 0 LO FREQUENCY (MHz) 40 60 80 Figure 36. Supply Current vs. Temperature 0 0 –5 –2 –10 –4 RETURN LOSS (dB) –15 –20 IF = 10MHz –30 –35 –6 –8 –10 –12 –40 05352-035 –14 IF = 48MHz –45 50 100 150 200 250 300 350 400 450 500 05352-059 FEEDTHROUGH (dBc) Figure 33. LO to RF Leakage vs. LO Frequency, LO Power = 0 dBm –25 20 TEMPERATURE (°C) –16 –18 60 550 160 260 360 RF FREQUENCY (MHz) 460 560 660 760 860 LO FREQUENCY (MHz) Figure 37. LO Return Loss vs. LO Frequency Figure 34. RF to IF Feedthrough, RF Power = −10 dBm 100pF 0 VPOS –5 1.82kΩ 0.1µF 100pF 12 11 10 9 VPDC PWDN EXRB COMM –15 –20 13 COMM COMM 8 IFOP 7 1nF –25 14 RFCM AD8342 100Ω RF IN 15 RFIN 16 VPMX –35 0.1µF –45 50 150 250 350 450 550 650 750 IFOM 6 COMM 5 1nF VPOS –40 IF OUT (50Ω) TC2-1T 100pF VPLO LOCM LOIN COMM 1 2 3 4 VPOS 100pF 850 0.1µF 100pF 1nF 0.1µF 1nF LO FREQUENCY (MHz) LO IN Figure 35. LO to IF Feedthrough vs. LO Frequency, LO Power = 0 dBm Figure 38. Characterization Circuit Used to Measure TPC Data Rev. 0 | Page 13 of 20 05352-058 –30 05352-020 FEEDTHROUGH (dBc) –10 AD8342 CIRCUIT DESCRIPTION The AD8342 is an active mixer optimized for operation within the input frequency range of near dc to 500 MHz. It has a differential, high impedance RF input that can be terminated or matched externally. The RF input can be driven either singleended or differentially. The LO input is a single-ended 50 Ω input. The IF outputs are differential open-collectors. The mixer current can be adjusted by the value of an external resistor to optimize performance for gain, compression, and intermodulation, or for low power operation. Figure 39 shows the basic blocks of the mixer, including the LO buffer, RF voltage-tocurrent converter, bias cell, and mixing core. VPDC EXTERNAL BIAS RESISTOR PWDN BIAS IFOP V TO I RFCM IFOM LO INPUT VPLO 05352-040 RFIN Figure 39. Simplified Schematic Showing the Key Elements of the AD8342 The device also features a power-down function. Application of a logic low at the PWDN pin allows normal operation. A high logic level at the PWDN pin shuts down the AD8342. Power consumption when the part is disabled is less than 10 mW. As shown in Figure 40, the IF output pins, IFOP and IFOM, are directly connected to the open collectors of the NPN transistors in the mixer core so the differential and single-ended impedances looking into this port are relatively high—on the order of several kΩ. A connection between the supply voltage and these output pins is required for proper mixer core operation. IFOP IFOM LOIN RFIN RFCM COMM 05352-041 The RF voltage to RF current conversion is done via a resistively degenerated differential pair. To drive this port single-ended, the RFCM pin should be ac-grounded while the RFIN pin is ac-coupled to the signal source. The RF inputs can also be driven differentially. The voltage-to-current converter then drives the emitters of a four-transistor switching core. This switching core is driven by an amplified version of the local oscillator signal connected to the LO input. There are three limiting gain stages between the external LO signal and the switching core. The first stage converts the single-ended LO drive to a well-balanced differential drive. The differential drive then passes through two more gain stages, which ensures a limited signal drives the switching core. This affords the user a lower LO drive requirement, while maintaining excellent distortion and compression performance. The output signal of these three LO gain stages drives the four transistors within the mixer core to commutate at the rate of the local oscillator frequency. The output of the mixer core is taken directly from its open collectors. The open collector outputs present a high impedance at the IF frequency. The conversion gain of the mixer depends directly on the impedance presented to these open collectors. In characterization, a 100 Ω load was presented to the part via a 2:1 impedance transformer. Figure 40. AD8342 Simplified Schematic The AD8342 has three pins for the supply voltage: VPDC, VPMX, and VPLO. These pins are separated to minimize or eliminate possible parasitic coupling paths within the AD8342 that could cause spurious signals or reduced interport isolation. Consequently, each of these pins should be well bypassed and decoupled as close to the AD8342 as possible. The bias for the mixer is set with an external resistor (RBIAS) from the EXRB pin to ground. The value of this resistor directly affects the dynamic range of the mixer. The external resistor should not be lower than 1.82 kΩ. Permanent damage to the part could result if values below 1.8 kΩ are used. This resistor sets the dc current through the mixer core. The performance effects of changing this resistor can be seen in the Typical Performance Characteristics section. Rev. 0 | Page 14 of 20 AD8342 AC INTERFACES Table 4. Dynamic Performance for Various Input Networks Input Network Gain (dB) IIP3 (dBm) P1dB (dBm) NF (dB) 50 Ω Shunt 0.66 25.4 10.8 14 100 Ω Shunt 3.5 22.9 8.4 12.5 500 Ω Shunt 5.3 20. 6 6.3 10.2 Matched (Fig. 40) 9.3 18.5 2.3 10.5 The RF port can also be matched using an LC circuit, as shown in Figure 42. 50Ω The AD8342 is designed to operate over a broad frequency range. It is essential to ac-couple RF and LO ports to prevent dc offsets from skewing the mixer core in an asymmetrical manner, potentially degrading noise figure and linearity. 100nH 3.6pF (1000 + j0) Ω 1kΩ ZL ZO = 50Ω fMAIN = 250MHz 05352-043 The AD8342 is designed to downconvert radio frequencies (RF) to lower intermediate frequencies (IF) using a high or low-side local oscillator (LO). The LO is injected into the mixer core at a frequency higher or lower than the desired input RF. The difference between the LO and the RF , fLO − fRF, (high side) or fRF − fLO (low side) is the intermediate frequency, fIF. In addition to the desired RF signal, an RF image is downconverted to the desired IF frequency. The image frequency is at fLO + fIF when driven with a high side LO . When using a broadband load, the conversion gain of the AD8342 is nearly constant over the specified RF input band (see Figure 3). Figure 42. Matching Circuit The RF input of the AD8342 is high impedance, 1 kΩ across the frequency range shown in Figure 41. The input capacitance decreases with frequency due to package parasitics. 2.00 1.00 1.75 0.75 1.25 1.00 0.50 0.75 0.50 CAPACITANCE (pF) RESISTANCE (kΩ) 1.50 Impedance transformations of greater than 10:1 result in a higher Q circuit and thus a narrow RF input bandwidth. A 1 kΩ resistor is placed across the RF input of the device in parallel with the device internal input impedance, creating a 500 Ω load. This impedance is matched to as close as possible to 50 Ω for the source, with standard components using a shunt C, series L matching circuit (see Figure 43). 50.0 100.0 25.0 Q = 3.0 0.25 200.0 0.25 0 100M 200M 300M 400M 500M 600M 700M 800M 900M FREQUENCY (Hz) 0 1G 500.0 Figure 41. RF Input Impedance 2 1 500.0 4 The matching or termination used at the RF input of the AD8342 has a direct effect on its dynamic range. The characterization circuit, as well as the evaluation board, uses a 100 Ω resistor to terminate the RF port. This termination resistor in shunt with the input stage results in a return loss of better than −10 dBm (relative to 50 Ω). Table 4 shows gain, IP3, P1dB, and noise figure for four different input networks. This data was measured at an RF frequency of 250 MHz and at an LO frequency of 300 MHz. 200.0 100.0 50.0 3 25.0 10.0 Point 1(1000.0 + j0.0)Ω Q = 0.0 at 250.000 MHz Point 2(500.0 + j0.0)Ω Q = 0.0 at 250.000 MHz Point 3(55.6 − j157.2)Ω Q = 2.8 at 250.000 MHz Point 4(55.6 − j0.1)Ω Q = 0.0 at 250.000 MHz Figure 43. LC Matching Example Rev. 0 | Page 15 of 20 05352-044 0 05352-042 10.0 AD8342 IF PORT The IF port comprises open-collector differential outputs. The NPN open collectors can be modeled as current sources that are shunted with resistances of ~10 kΩ in parallel with capacitances of ~1 pF. The specified performance numbers for the AD8342 were measured with 100 Ω differential terminations. However, different load impedances may be used where circumstances dictate. In general, lower load impedances result in lower conversion gain and lower output P1dB. Higher load impedances result in higher conversion gain for small signals, but lower IP3 values for both input and output. If the IF signal is to be delivered to a remote load, more than a few millimeters away at high output frequencies, avoid unintended parasitic effects due to the intervening PCB traces. One approach is to use an impedance transforming network or transformer located close to the AD8342. If very wideband output is desired, a nearby buffer amplifier may be a better choice, especially if IF response to dc is required. An example of such a circuit is presented in Figure 45, in which the AD8351 differential amplifier is used to drive a pair of 75 Ω transmission lines. The gain of the buffer can be independently set by appropriate choice of the value for the gain resistor, RG. 50 0.5 45 0.4 30 0.2 25 0.1 20 15 CAPACITANCE (pF) RESISTANCE (kΩ) 0.3 It is necessary to bias the open-collector outputs using one of the schemes presented in Figure 47 and Figure 48. Figure 47 illustrates the application of a center tapped impedance transformer. The turns ratio of the transformer should be selected to provide the desired impedance transformation. In the case of a 50 Ω load impedance, a 2-to-1 impedance ratio transformer should be used to transform the 50 Ω load into a 100 Ω differential load at the IF output pins. Figure 48 illustrates a differential IF interface where pull-up choke inductors are used to bias the open-collector outputs. The shunting impedance of the choke inductors used to couple dc current into the mixer core should be large enough at the IF operating frequency so it does not load down the output current before reaching the intended load. Additionally, the dc current handling capability of the selected choke inductors needs to be at least 45 mA. The selfresonant frequency of the selected choke should be higher than the intended IF frequency. A variety of suitable choke inductors are commercially available from manufacturers such as Murata and Coilcraft. Figure 46 shows the loading effects when using nonideal inductors. An impedance transforming network may be required to transform the final load impedance to 100 Ω at the IF outputs. There are several good reference books that explain general impedance matching procedures, including: • Chris Bowick, RF Circuit Design, Newnes, Reprint Edition, 1997. 40 35 The high input impedance of the AD8351 allows for a shunt differential termination to provide the desired 100 Ω load to the AD8342 IF output port. • David M. Pozar, Microwave Engineering, Wiley Text Books, Second Edition, 1997. • Guillermo Gonzalez, Microwave Transistor Amplifiers: Analysis and Design, Prentice Hall, Second Edition, 1996. 0 10 90 –0.1 5 60 0 100M 200M 300M 400M 500M 600M 700M 800M 900M –0.2 1G FREQUENCY (Hz) 05352-045 120 0 Figure 44. IF Port Impedance 150 30 50MHz +VS REAL CHOKES AD8342 +VS COMM 8 180 RFC 0 50MHz IFOP 7 RG IFOM 6 + AD8351 – Tx LINE ZO = 75Ω 500MHz ZL Tx LINE ZO = 75Ω 210 330 RFC +VS 500MHz ZL = 100Ω 05352-046 COMM 5 IDEAL CHOKES Figure 45. AD8351 Used as Transmission Line Driver and Impedance Buffer 240 300 270 05352-049 100Ω Figure 46. IF Port Loading Effects Due to Finite Q Pull-Up Inductors (Murata BLM18HD601SN1D Chokes) Rev. 0 | Page 16 of 20 AD8342 30 +VS AD8342 MODELED 25 COMM 8 IF OUT ZO = 50Ω VOLTAGE GAIN (dB) 2:1 IFOP 7 COMM 5 ZL = 100Ω 05352-047 IFOM 6 Figure 47. Biasing the IF Port Open-Collector Outputs Using a Center-Tapped Impedance Transformer +VS 20 MEASURED 15 10 05352-057 5 AD8342 0 10 RFC IF OUT+ IFOP 7 ZL = 100Ω IFOM 6 IMPEDANCE TRANSFORMING NETWORK Figure 49. Voltage Conversion Gain vs. IF Loading IF OUT– LO CONSIDERATIONS 05352-048 +VS The LOIN port provides a 50 Ω load impedance with commonmode decoupling on LOCM. Again, common-grade ceramic capacitors provide sufficient signal coupling and bypassing of the LO interface. Figure 48. Biasing the IF Port Open-Collector Outputs Using Pull-Up Choke Inductors The AD8342 is optimized for driving a 100 Ω load. Although the device is capable of driving a wide variety of loads, to maintain optimum distortion and noise performance, it is advised that the presented load at the IF outputs is close to 100 Ω. The linear differential voltage conversion gain of the mixer can be modeled as Av = Gm × RLOAD where: Gm = 1 1000 ZL RFC COMM 5 100 IF LOAD (Ω) gm π 1 + g m Re RLOAD is the single-ended load impedance. gm is the transistor transconductance and is equal to 1810/RBIAS. Re is 15 Ω. The external RBIAS resistor is used to control the power dissipation and dynamic range of the AD8342. Because the AD8342 has internal resistive degeneration, the conversion gain is primarily determined by the load impedance and the on-chip degeneration resistors. Figure 49 shows how gain varies with IF load. The external RBIAS resistor has only a small effect. The most direct way to affect conversion gain is by varying the load impedance. Small loads result in lower gains while larger loads increase the conversion gain. If the IF load impedance is too large it causes a decrease in linearity (P1dB, IP3). In order to maintain positive conversion gain and preserve SFDR performance, the differential load presented at the IF port should remain in the range of ~ 100 Ω to 250 Ω. The LO signal needs to have adequate phase noise characteristics and low second-harmonic content to prevent degradation of the noise figure performance of the AD8342. An LO plagued with poor phase noise can result in reciprocal mixing, a mechanism that causes spectral spreading of the downconverted signal, limiting the sensitivity of the mixer at frequencies close-in to any large input signals. The internal LO buffer provides enough gain to hard-limit the input LO and provide fast switching of the mixer core. Odd harmonic content present on the LO drive signal should not impact mixer performance; however, even-order harmonics cause the mixer core to commutate in an unbalanced manner, potentially degrading noise performance. Simple lumped element low-pass filtering can be applied to help reject the harmonic content of a given local oscillator, as shown in Figure 50. The filter depicted is a common 3-pole Chebyshev, designed to maintain a 1-to-1 source-to-load impedance ratio with no more than 0.5 dB of ripple in the pass band. Other filter structures can be effective as long as the second harmonic of the LO is filtered to negligible levels, for example, ~30 dB below the fundamental. AD8342 LOCM LOIN COMM 2 RS 3 4 L2 LO SOURCE C1 C3 RL FOR RS = RL C1 = 1.864 2πfcRL L2 = 1.28RL 2πfc C3 = fC - FILTER CUTOFF FREQUENCY 1.834 2πfcRL 05352-050 COMM 8 Figure 50. Using a Low-Pass Filter to Reduce LO Second Harmonic Rev. 0 | Page 17 of 20 AD8342 HIGH IF APPLICATIONS production concerns due to the sensitivity of the match. For this application, it is advantageous to shunt down the ~1 kΩ input impedance using an external shunt termination resistor to allow for a lower Q reactive matching network. The input is terminated across the RFIN and RFCM pins using a 499 Ω termination. The termination should be as close to the device as possible to minimize standing wave concerns. The RFCM is bypassed to ground using a 1 nF capacitor. A dc blocking capacitor of 1 nF is used to isolate the dc input voltage present on the RFIN pin from the source. A step-up impedance transformation is realized using a series L shunt C reactive network. The actual values used need to accommodate for the series L and stray C parasitics of the connecting transmission line segments. When using the customer evaluation board with the components specified in Figure 51, the return loss over a 5 MHz band centered at 170 MHz was better than 10 dB. In some applications it may be desirable to use the AD8342 as an up-converting mixer. The AD8342 is a broadband mixer capable of both up and down conversion. Unlike other mixers that rely on on-chip reactive circuitry to optimize performance over a specific band, the AD8342 is a versatile general-purpose device that can be used from arbitrarily low frequencies to several GHz. In general, the following considerations help to ensure optimum performance: • • • • Minimize ac loading impedance of IF port bias network. Maximize power transfer to the desired ac load. For maximum conversion gain and the lowest noise performance reactively match the input as described in the IF Port section. For maximum input compression point and input intercept points resistively terminate the input as described in the IF Port section. External pull-up choke inductors are used to feed dc bias into the open-collector outputs. It is desirable to select pull-up choke inductors that present high loading reactance at the output frequency. Coilcraft 0302CS series inductors were selected due to their very high self-resonant frequency and Q. A 1:1 balun was ac-coupled to the output to convert the differential output to a single-ended signal and present the output with a 50 Ω ac loading impedance. As an example, Figure 51 shows the AD8342 as an upconverting mixer for a WCDMA single-carrier transmitter design. For this application, it was desirable to achieve −65 dBc adjacent channel power ratio (ACPR) at a −13 dBm output power level. The ACPR is a measure of both distortion and noise carried into an adjacent frequency channel due to the finite intercept points and noise figure of an active device. 100pF VPOS 1.82kΩ 0.1pF 100pF VPOS 12 11 10 9 VPDC PWDN EXRB COMM 13 COMM COMM 8 IFOP 7 100pF 34nH 1nF ETC1-1-13 14 RFCM 100nH 170MHz INPUT 1nF 499Ω AD8342 1nF 15 RFIN 4.7pF IFOM 1nF VPOS 16 VPMX 0.1µF 2140MHz OUT 6 The performance of the circuit is shown in Figure 52. The average ACPR of the adjacent and alternate channels is presented vs. output power. The circuit provides a 65 dBc ACPR at −13 dBm output power. The optimum ACPR power level can be shifted to the right or left by adjusting the output loading and the loss of the input match. 100pF COMM 5 VPLO LOCM LOIN COMM 1 2 3 4 –60 34nH 100pF VPOS ADJACENT CHANNELS –62 1nF 1nF Figure 51. WCDMA Tx Up-Conversion Application Circuit Because a WCDMA channel encompasses a bandwidth of almost 5 MHz, it is necessary to keep the Q of the matching circuit low enough so that phase and magnitude variations are below an acceptable level over the 5 MHz band. It is possible to use purely reactive matching to transform a 50 Ω source to match the raw ~1 kΩ input impedance of the AD8342. However, the L and C component variations could present –64 –66 ALTERNATE CHANNELS –68 –70 –25 05352-053 1970MHz OSC ACPR (dBc) 05352-052 100pF –20 –15 –10 –5 0 OUTPUT POWER (dBm) Figure 52. Single Carrier WCDMA ACPR Performance of Tx Up-Conversion Circuit (Test Model 1_64) Rev. 0 | Page 18 of 20 AD8342 EVALUATION BOARD An evaluation board is available for the AD8342. The evaluation board is configured for single-ended signaling at the IF output port via a balun transformer. The schematic for the evaluation board is presented in Figure 53. R8 PWDN C11 100pF 10kΩ W1 GND VPOS VPOS R7 C12 0.1µF 0Ω R6 R9 0Ω 1.82kΩ C13 100pF 12 9 10 11 Z2 OPEN VPDC PWDN EXRB COMM 13 L1 0Ω 50Ω TRACE RF_IN C14 OPEN R5 100Ω R10 0Ω COMM 8 COMM C1 1000pF 14 IFOP 7 RFCM C3 1000pF 15 DUT Z3 OPEN RFIN IFOM 6 R1 VPOS 16 C2 0.1µF 0Ω C4 1000pF COMM 5 VPMX 1 2 3 4 C5 0.1µF 0Ω C6 1000pF 3 2 1 R11 6 100Ω TRACES, NO GROUND PLANE R4 OPEN Z4 OPEN IF_OUT– R15 0Ω R16 C8 1000pF 4 TC2-1T 0Ω 0Ω C7 1000pF IF_OUT+ T1 Z1 OPEN R12 OPEN VPLO LOCM LOIN COMM R2 R3 OPEN VPOS C10 100pF C9 0.1µF 05352-003 PWDN INLO Figure 53. Evaluation Board Table 6. Evaluation Board Configuration Options Component R1, R2, R7, C2, C4, C5, C6, C10 C12, C13, C14, C9 Function Supply decoupling. Shorts or power supply decoupling resistors and filter capacitors. R3, R4 R15, 16 R6, C11 Options for single-ended IF output circuit. R8 R9 C3, R5, C16, L1 C1 C8 C7 W1 T1, R12, R11, Z3, Z4, Z1, Z2, R10 RBIAS resistor that sets the bias current for the mixer core. The capacitor provides ac bypass for R6. Pull down for the PWDN pin. Link to PWDN pin. RF input. C3 provides dc block for RF input. R5 provides a resistive input termination. C16 and L1 are provided for reactive matching the input. RF common ac coupling. Provides dc block for RF input common connection. LO input ac coupling. Provides dc block for the LO input. LO common ac coupling. Provides dc block for LO input common connection. Power down. The part is on when the PWDN is connected to ground via a 10 kΩ resistor. The part is disabled when PWDN is connected to the positive supply (VS) via W1. IF output interface. T1 converts a differential high impedance IF output to single-ended. When loaded with 50 Ω, this balun presents a 100 Ω load to the mixers collectors. The center tap of the primary is used to supply the bias voltage (VS) to the IF output pins. Rev. 0 | Page 19 of 20 Default Conditions R1, R2, R7 = 0 Ω C4, C6 = 1000 pF C10, C13 = 100 pF C2, C5, C12, C9 = 0.1 µF R3, R4 = Open Ω R15, R16 = 0 Ω R6 = 1.82 kΩ C11 = 100 pF R8 = 10 kΩ R9 = 0 Ω C3 = 1000 pF R5 = 100 Ω C14 = Open L1 = 0 Ω C1 = 1000 pF C7, C8 = 1000 pF T1 = TC2-1T, 2:1 (Mini-Circuits) R12 = Open Ω R10, R11 = 0 Ω Z3, Z4 = Open Z1, Z2 = Open AD8342 Preliminary Technical Data OUTLINE DIMENSIONS 3.00 BSC SQ 0.60 MAX 13 12 0.45 PIN 1 INDICATOR TOP VIEW 2.75 BSC SQ 0.80 MAX 0.65 TYP 12° MAX SEATING PLANE 16 PIN 1 INDICATOR *1.65 1 1.50 SQ 1.35 EXPOSED PAD 0.50 BSC 0.90 0.85 0.80 0.50 0.40 0.30 9 (BOTTOM VIEW) 4 8 5 0.25 MIN 1.50 REF 0.05 MAX 0.02 NOM 0.30 0.23 0.18 0.20 REF *COMPLIANT TO JEDEC STANDARDS MO-220-VEED-2 EXCEPT FOR EXPOSED PAD DIMENSION. Figure 54. 16-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 3 mm x 3 mm Body, Very Thin Quad (CP-16-3) Dimensions in millimeters ORDERING GUIDE Models AD8342ACPZ-REEL71 Temperature Package −40°C to +85°C AD8342ACPZ-R21 −40°C to +85°C AD8342ACPZ-WP1 −40°C to +85°C AD8342-EVAL 1 Package Description 16-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 16-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 16-Lead Lead Frame Chip Scale Package [LFCSP_VQ] Evaluation Board Z = Pb-free part. © 2005 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D05352–0–4/05(0) Rev. 0 | Page 20 of 20 Package Outline CP-16-3 Branding Q01 Transport Media, Quanity 1,500, Reel CP-16-3 Q01 250, Reel CP-16-3 Q01 50, Waffle Pack 1