19-3404; Rev 1; 10/06 KIT ATION EVALU E L B A AVAIL LF-to-2.5GHz Dual Logarithmic Detector/ Controller for Power, Gain, and VSWR Measurements The MAX2016 dual logarithmic detector/controller is a fully integrated system designed for measuring and comparing power, gain/loss, and voltage standing-wave ratio (VSWR) of two incoming RF signals. An internal broadband impedance match on the two differential RF input ports allows for the simultaneous monitoring of signals ranging from low frequency to 2.5GHz. The MAX2016 uses a pair of logarithmic amplifiers to detect and compare the power levels of two RF input signals. The device internally subtracts one power level from the other to provide a DC output voltage that is proportional to the power difference (gain). The MAX2016 can also measure the return loss/VSWR of an RF signal by monitoring the incident and reflected power levels associated with any given load. A window detector is easily implemented by using the on-chip comparators, OR gate, and 2V reference. This combination of circuitry provides an automatic indication of when the measured gain is outside a programmable range. Alarm monitoring can thus be implemented for detecting high-VSWR states (such as open or shorted loads). The MAX2016 operates from a single +2.7V to +5.25V* power supply and is specified over the extended -40C to +85C temperature range. The MAX2016 is available in a space-saving, 5mm x 5mm, 28-pin thin QFN. Applications Return Loss/VSWR Measurements Dual-Channel RF Power Measurements Dual-Channel Precision AGC/RF Power Control Log Ratio Function for RF Signals Remote System Monitoring and Diagnostics Features Complete Gain and VSWR Detector/Controller Dual-Channel RF Power Detector/Controller Low-Frequency to 2.5GHz Frequency Range Exceptional Accuracy Over Temperature High 80dB Dynamic Range 2.7V to 5.25V Supply Voltage Range* Internal 2V Reference Scaling Stable Over Supply and Temperature Variations Controller Mode with Error Output Available in 5mm x 5mm, 28-Pin Thin QFN Package *See Power-Supply Connection section. Ordering Information TEMP RANGE PINPACKAGE MAX2016ETI -40C to +85C 28 Thin QFN-EP*, T2855-3 bulk MAX2016ETI-T -40C to +85C 28 Thin QFN-EP*, T2855-3 T/R MAX2016ETI+D -40C to +85C 28 Thin QFN-EP*, T2855-3 lead free, bulk MAX2016ETI+TD -40C to +85C 28 Thin QFN-EP*, T2855-3 lead free, T/R PART *EP = Exposed pad. +Indicates lead-free package. D = Dry pack. Pin Configuration OUTA SETA REF SETB OUTB FB2 RF/IF Power Amplifier (PA) Linearization FA2 Cellular Base Station, Microwave Link, Radar, and other Military Applications 28 27 26 25 24 23 22 FA1 1 21 FB1 VCC 2 20 VCC RFINA+ 3 RFINA- 4 GND 5 17 GND COUTH 6 16 COUTL CSETH 7 15 CSETL 19 RFINB+ MAX2016 8 9 10 11 12 13 14 VCC SETD OUTD VCC FV2 FV1 18 RFINB- COR Typical Application Circuit appears at end of data sheet. PKG CODE THIN QFN ________________________________________________________________ Maxim Integrated Products 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. 1 MAX2016 General Description MAX2016 LF-to-2.5GHz Dual Logarithmic Detector/ Controller for Power, Gain, and VSWR Measurements ABSOLUTE MAXIMUM RATINGS VCC to GND .........................................................-0.3V to +5.25V Input Power Differential (RFIN_+, RFIN_-)......................+23dBm Input Power Single Ended (RFIN_+ or RFIN _-) .............+19dBm All Other Pins to GND.................................-0.3V to (VCC + 0.3V) Continuous Power Dissipation (TA = +70C) 28-Pin, 5mm x 5mm Thin QFN (derate 35.7mW/C above +70C)..................................................................2.8W Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. DC ELECTRICAL CHARACTERISTICS (VCC = +2.7V to +3.6V, R1 = R2 = R3 = 0, TA = -40C to +85C, unless otherwise noted. Typical values are at VCC = +3.3V, CSETL = CSETH = VCC, 50 RF system, TA = +25C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS POWER SUPPLY Supply Voltage Total Supply Current VS R6 = 0 2.7 3.3 3.6 VS R6 = 37.4 4.75 5 5.25 43 55 ICC Supply Current Measured in each pin 2 and pin 20 16 Measured in pin 9 2 Measured in pin 12 9 Differential impedance at RFINA and RFINB 50 V mA mA INPUT INTERFACE Input Impedance Input Resistance R Resistance at SETD 20 Resistance at SETA and SETB 40 k DETECTOR OUTPUT Source Current Measured at OUTA, OUTB, and OUTD 4 mA Sink Current Measured at OUTA, OUTB, and OUTD 0.45 mA Minimum Output Voltage Measured at OUTA, OUTB, and OUTD 0.5 V Maximum Output Voltage Measured at OUTA, OUTB, and OUTD 1.8 V Difference Output VOUTD PRFINA = PRFINB = -30dBm 1 V 12 mV OUTD Accuracy COMPARATORS Output High Voltage VOH RLOAD 10k VCC 10mV V Output Low Voltage VOL RLOAD 10k 10 mV GND to VCC V 1 nA Input Voltage Measured at CSETL and CSETH Input Bias Current CSETL and CSETH REFERENCE Output Voltage on Pin 25 RLOAD 2k 2 V Load Regulation Source 2mA -5 mV 2 _______________________________________________________________________________________ LF-to-2.5GHz Dual Logarithmic Detector/ Controller for Power, Gain, and VSWR Measurements (Typical Application Circuit, VCC = +2.7V to +3.3V, R1 = R2 = R3 = 0, TA = -40C to +85C, unless otherwise noted. Typical values are at VCC = 3.3V, CSETL = CSETH = VCC, TA = +25C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL RF Input Frequency Range fRF Return Loss S11 Large-Signal Response Time CONDITIONS MIN TYP AC-coupled input MAX UNITS 2.5 GHz 0.1GHz to 3GHz 20 dB PRFIN = no signal to 0dBm, 0.5dB settling accuracy 100 ns -70 to +10 dBm RSSI MODE--0.1GHz RF Input Power Range (Note 2) 3dB Dynamic Range TA = -20C to +85C (Note 3) Range Center 80 dB -32 dBm TA = +25C to +85C +0.0083 TA = +25C to -20C -0.0083 Temperature Sensitivity PRFINA = PRFINB = -32dBm Slope (Note 4) Typical Slope Variation TA = -20C to +85C Intercept (Note 5) -100 dBm Typical Intercept Variation TA = -20C to +85C 0.03 dBm/C -70 to +10 dBm dB/C 19 mV/dB -4 V/C RSSI MODE--0.9GHz RF Input Power Range (Note 2) 3dB Dynamic Range TA = -20C to +85C (Note 3) Range Center Temperature Sensitivity PRFINA = PRFINB = -30dBm 80 dB -30 dBm TA = +25C to +85C +0.0083 TA = +25C to -20C -0.0083 dB/C Slope (Note 4) Typical Slope Variation TA = -20C to +85C 18.1 mV/dB -4 V/C Intercept (Note 5) -97 dBm Typical Intercept Variation TA = -20C to +85C 0.02 dBm/C -55 to +12 dBm 67 dB -27 dBm RSSI MODE--1.9GHz RF Input Power Range (Note 2) 3dB Dynamic Range TA = -20C to +85C (Note 3) Range Center Temperature Sensitivity PRFINA = PRFINB = -27dBm TA = +25C to +85C +0.0125 TA = +25C to -20C -0.0125 dB/C Slope (Note 4) 18 mV/dB Typical Slope Variation TA = -20C to +85C -4.8 V/C Intercept (Note 5) -88 dBm Typical Intercept Variation TA = -20C to +85C 0.03 dBm/C _______________________________________________________________________________________ 3 MAX2016 AC ELECTRICAL CHARACTERISTICS--OUTA AND OUTB MAX2016 LF-to-2.5GHz Dual Logarithmic Detector/ Controller for Power, Gain, and VSWR Measurements AC ELECTRICAL CHARACTERISTICS--OUTA AND OUTB (continued) (Typical Application Circuit, VCC = +2.7V to +3.3V, R1 = R2 = R3 = 0, TA = -40C to +85C, unless otherwise noted. Typical values are at VCC = 3.3V, CSETL = CSETH = VCC, TA = +25C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS RSSI MODE--2.17GHz -52 to +12 RF Input Power Range (Note 2) 3dB Dynamic Range TA = -20C to +85C (Note 3) Range Center Temperature Sensitivity PRFINA = PRFINB = -25dBm Slope (Note 4) Typical Slope Variation Intercept dBm 64 dB -25 dBm TA = +25C to +85C +0.0135 TA = +25C to -20C -0.0135 dB/C 17.8 mV/dB TA = -20C to +85C -8 V/C (Note 5) -81 dBm Typical Intercept Variation RSSI MODE--2.5GHz TA = -20C to +85C 0.03 dBm/C RF Input Power Range (Note 2) 3dB Dynamic Range TA = -20C to +85C (Note 3) -45 to +7 52 Range Center dBm dB -23 PRFINA = PRFINB = -23dBm Temperature Sensitivity TA = +25C to +85C TA = +25C to -20C dBm +0.0167 -0.0167 17.8 mV/dB dB/C Slope (Note 4) Typical Slope Variation TA = -20C to +85C -8 V/C Intercept (Note 5) -80 dBm Typical Intercept Variation TA = -20C to +85C 0.03 dBm/C AC ELECTRICAL CHARACTERISTICS--OUTD (Typical Application Circuit, VCC = +2.7V to +3.3V, R1 = R2 = R3 = 0, TA = -40C to +85C, unless otherwise noted. Typical values are at VCC = 3.3V, CSETL = CSETH = VCC, TA = +25C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS OUTD Center Point PRFINA = PRFINB 1 V Small-Signal Envelope Bandwidth No external capacitor on pins FV1 and FV2 22 MHz Small-Signal Settling Time Any 8dB change on the inputs, no external capacitor on FV1 and FV2, settling accuracy is 0.5dB 150 ns Large-Signal Settling Time Any 30dB change on the inputs, no external capacitor on pins FV1 and FV2, settling accuracy is 0.5dB 300 ns Small-Signal Rise and Fall Time Any 8dB step, no external capacitor on pins FV1 and FV2 15 ns 4 _______________________________________________________________________________________ LF-to-2.5GHz Dual Logarithmic Detector/ Controller for Power, Gain, and VSWR Measurements (Typical Application Circuit, VCC = +2.7V to +3.3V, R1 = R2 = R3 = 0, TA = -40C to +85C, unless otherwise noted. Typical values are at VCC = 3.3V, CSETL = CSETH = VCC, TA = +25C, unless otherwise noted.) (Note 1) PARAMETER Large-Signal Rise and Fall Time 1dB Dynamic Range SYMBOL CONDITIONS 0.1GHz PRFINB = -32dBm 80 0.9GHz PRFINB = -30dBm 75 1.9GHz PRFINB = -27dBm 60 2.17GHz PRFINB = -25dBm 55 2.5GHz PRFINB = -23dBm fRF = 0.1GHz to 2.5GHz (A-B) OUTD Voltage Deviation PRFINA = PRFINB = -30dBm, TA = -20C to +85C Gain Measurement Balance Channel Isolation TYP 35 Slope 1dB Dynamic Range over Temperature Relative to Best-Fit Curve at +25C MIN Any 30dB step, no external capacitor on pins FV1 and FV2 PRFINA is swept ; TA = -20C to +85C MAX UNITS ns dB 50 -25 0.25 0.1GHz, PRFINB = -32dBm 80 0.9GHz, PRFINB = -30dBm 70 1.9GHz, PRFINB = -27dBm 55 2.17GHz, PRFINB = -25dBm 50 2.5GHz, PRFINB = -23dBm 45 PRFINB = PRFINB = -50dBm to -5dBm, fRF = 1.9GHz 0.2 0.9GHz 90 1.9GHz 65 2.5GHz 55 mV/dB dB dB dB dB The MAX2016 is tested at TA = +25C and is guaranteed by design for TA = -40C to +85C. Typical minimum and maximum range of the detector at the stated frequency. Dynamic range refers to the range over which the error remains within the 3dB range. The slope is the variation of the output voltage per change in input power. It is calculated by fitting a root-mean-square straight line to the data indicated by the RF input power range. Note 5: The intercept is an extrapolated value that corresponds to the output power for which the output voltage is zero. It is calculated by fitting a root-mean-square straight line to the data. Note 1: Note 2: Note 3: Note 4: _______________________________________________________________________________________ 5 MAX2016 AC ELECTRICAL CHARACTERISTICS--OUTD (continued) Typical Operating Characteristics (MAX2016 EV kit, VCC = 3.3V, R1 = R2 = R3 = 0, CSETL = CSETH = VCC, TA = +25C, unless otherwise noted.) DIFFERENTIAL OUTPUT VOLTAGE vs. A/B DIFFERENCE fIN = 100MHz PRFINB = -32dBm NORMALIZED TO DATA AT +25C 2 1 ERROR (dB) TA = -20C, +25C, +85C 1.5 3 1.0 TA = -20C 0 TA = +85C -1 0.5 -2 0 -3 -10 10 30 -50 -30 -10 10 30 50 MAGNITUDE RATIO (dB) MAGNITUDE RATIO (dB) DIFFERENTIAL OUTPUT VOLTAGE vs. A/B DIFFERENCE DIFFERENTIAL OUTPUT-VOLTAGE ERROR vs. A/B DIFFERENCE fIN = 900MHz PRFINB = -30dBm PRFINA IS SWEPT 2.0 fIN = 900MHz PRFINB = -30dBm NORMALIZED TO DATA AT +25C 2 1 TA = -20C, +25C, +85C 1.5 3 ERROR (dB) 1.0 TA = -20C 0 TA = +85C -1 0.5 -2 0 -3 -30 -10 10 30 -50 -30 -10 10 30 50 MAGNITUDE RATIO (dB) MAGNITUDE RATIO (dB) DIFFERENTIAL OUTPUT VOLTAGE vs. A/B DIFFERENCE DIFFERENTIAL OUTPUT-VOLTAGE ERROR vs. A/B DIFFERENCE 2.5 fIN = 1900MHz PRFINB = -27dBm PRFINA IS SWEPT TA = -20C 2.0 50 3 MAX2016 toc05 -50 fIN = 1900MHz PRFINB = -27dBm NORMALIZED TO DATA AT +25C 2 TA = +25C MAX2016 toc06 VOUTD (V) 50 MAX2016 toc04 2.5 -30 MAX2016 toc03 -50 ERROR (dB) 1 1.5 TA = +85C 1.0 TA = -20C 0 -1 0.5 TA = +85C -2 0 -3 -40 -20 0 20 MAGNITUDE RATIO (dB) 6 MAX2016 toc02 fIN = 100MHz PRFINB = -32dBm PRFINA IS SWEPT 2.0 VOUTD (V) DIFFERENTIAL OUTPUT-VOLTAGE ERROR vs. A/B DIFFERENCE MAX2016 toc01 2.5 VOUTD (V) MAX2016 LF-to-2.5GHz Dual Logarithmic Detector/ Controller for Power, Gain, and VSWR Measurements 40 -40 -20 0 20 40 MAGNITUDE RATIO (dB) _______________________________________________________________________________________ LF-to-2.5GHz Dual Logarithmic Detector/ Controller for Power, Gain, and VSWR Measurements DIFFERENTIAL OUTPUT VOLTAGE vs. A/B DIFFERENCE TA = -20C TA = +85C 1.5 fIN = 2170MHz PRFINB = -25dBm NORMALIZED TO DATA AT +25C 2 1 ERROR (dB) TA = +25C 1.0 TA = -20C 0 -1 0.5 -2 0 -3 -25 2.5 -5 15 35 -20 0 40 20 MAGNITUDE RATIO (dB) DIFFERENTIAL OUTPUT VOLTAGE vs. A/B DIFFERENCE DIFFERENTIAL OUTPUT-VOLTAGE ERROR vs. A/B DIFFERENCE fIN = 2500MHz PRFINB = -23dBm PRFINA IS SWEPT 2.0 -40 MAGNITUDE RATIO (dB) TA = -20C fIN = 2500MHz PRFINB = -23dBm NORMALIZED TO DATA AT +25C TA = -20C 2 1 ERROR (dB) TA = +25C 1.5 3 MAX2016 toc09 -45 VOUTD (V) TA = +85C TA = +85C 1.0 MAX2016 toc10 VOUTD (V) 2.0 3 MAX2016 toc08 fIN = 2170MHz PRFINB = -25dBm PRFINA IS SWEPT MAX2016 toc07 2.5 DIFFERENTIAL OUTPUT-VOLTAGE ERROR vs. A/B DIFFERENCE 0 -1 TA = +85C 0.5 -2 0 -3 -20 0 20 40 -40 -20 MAGNITUDE RATIO (dB) DIFFERENTIAL OUTPUT-VOLTAGE BALANCE VOUTD (V) 1.00 TA = +85C 0.95 -15 TA = -20C -20 -25 TA = +85C TA = +25C -30 -35 -40 -45 TA = +25C TA = -20C PRFINA = PRFINB - 5dB 0.90 S11 MAGNITUDE MAGNITUDE (dB) fIN = 1900MHz TA = +25C TA = +85C T = -20C A TA = +25C PRFINA = PRFINB + 5dB TA = +85C PRFINA = PRFINB TA = -20C 1.05 40 20 -10 MAX2016 toc11 1.15 1.10 0 MAGNITUDE RATIO (dB) MAX2016 toc12 -40 -50 -55 0.85 -60 -60 -45 -30 PRFINA (dBm) -15 0 0 0.5 1.0 1.5 2.0 2.5 3.0 FREQUENCY (GHz) _______________________________________________________________________________________ 7 MAX2016 Typical Operating Characteristics (continued) (MAX2016 EV kit, VCC = 3.3V, R1 = R2 = R3 = 0, CSETL = CSETH = VCC, TA = +25C, unless otherwise noted.) Typical Operating Characteristics (continued) (MAX2016 EV kit, VCC = 3.3V, R1 = R2 = R3 = 0, CSETL = CSETH = VCC, TA = +25C, unless otherwise noted.) VOUTA vs. PRFINA VOUTA ERROR vs. PRFINA TA = -20C TA = +25C 2.0 fIN = 100MHz NORMALIZED TO DATA AT +25C 2 1 ERROR (dB) 1.0 TA = -20C 0 TA = +85C -1 0.5 -2 0 -3 -60 -40 -20 0 20 -80 -60 -40 PRFINA (dBm) VOUTA vs. PRFINA 3 MAX2016 toc15 fIN = 900MHz TA = -20C TA = +25C fIN = 900MHz NORMALIZED TO DATA AT +25C 2 ERROR (dB) VOUTA (V) 1 TA = +85C 1.5 20 0 VOUTA ERROR vs. PRFINA 2.5 2.0 -20 PRFINA (dBm) 1.0 TA = -20C 0 TA = +85C -1 0.5 MAX2016 toc16 -80 -2 0 -3 -80 -60 -40 -20 0 20 -75 -60 -45 PRFINA (dBm) VOUTA vs. PRFINA 0 3 MAX2016 toc17 TA = -20C 2.0 -15 15 VOUTA ERROR vs. PRFINA 2.5 fIN = 1900MHz -30 PRFINA (dBm) TA = +25C MAX2016 toc18 VOUTA (V) TA = +85C 1.5 MAX2016 toc14 fIN = 100MHz 3 MAX2016 toc13 2.5 fIN = 1900MHz NORMALIZED TO DATA AT +25C 2 1.5 TA = +85C 1.0 ERROR (dB) 1 VOUTA (V) MAX2016 LF-to-2.5GHz Dual Logarithmic Detector/ Controller for Power, Gain, and VSWR Measurements TA = -20C 0 TA = +85C -1 0.5 -2 0 -3 -65 -45 -25 PRFINA (dBm) 8 -5 15 -65 -45 -25 -5 PRFINA (dBm) _______________________________________________________________________________________ 15 LF-to-2.5GHz Dual Logarithmic Detector/ Controller for Power, Gain, and VSWR Measurements VOUTA ERROR vs. PRFINA VOUTA vs. PRFINA TA = -20C 1 ERROR (dB) 1.5 TA = +85C 1.0 TA = -20C 0 -1 0.5 TA = +85C -2 -3 0 -60 -45 -30 -15 0 -60 15 -45 TA = -20C TA = +25C fIN = 2500MHz NORMALIZED TO DATA AT +25C 2 15 TA = -20C 1 ERROR (dB) VOUTA (V) 0 3 MAX2016 toc21 fIN = 2500MHz 1.5 1.0 -15 VOUTA ERROR vs. PRFINA VOUTA vs. PRFINA 2.5 2.0 -30 PRFINA (dBm) PRFINA (dBm) TA = +85C MAX2016 toc22 VOUTA (V) fIN = 2170MHz NORMALIZED TO DATA AT +25C 2 TA = +25C MAX2016 toc20 fIN = 2170MHz 2.0 3 MAX2016 toc19 2.5 0 -1 0.5 TA = +85C -2 -3 0 -60 -45 -30 -15 PRFINA (dBm) 0 15 -60 -45 -30 -15 0 15 PRFINA (dBm) _______________________________________________________________________________________ 9 MAX2016 Typical Operating Characteristics (continued) (MAX2016 EV kit, VCC = 3.3V, R1 = R2 = R3 = 0, CSETL = CSETH = VCC, TA = +25C, unless otherwise noted.) MAX2016 LF-to-2.5GHz Dual Logarithmic Detector/ Controller for Power, Gain, and VSWR Measurements Pin Description PIN NAME FUNCTION 1, 28 FA1, FA2 External Capacitor Input. Connecting a capacitor between FA1 and FA2 sets the highpass cutoff frequency corner for detector A (see the Input Highpass Filter section). 2, 9, 12, 20 VCC Supply Voltage. Bypass with capacitors as specified in the Typical Application Circuit. Place capacitors as close to each VCC as possible (see the Power-Supply Connections section). 3, 4 RFINA+, RFINA- 5, 17 GND Differential RF Inputs for Detector A. Requires external DC-blocking capacitors. 6 COUTH High-Comparator Output 7 CSETH Threshold Input on High Comparator 8 COR 10 SETD Set-Point Input for Gain Detector 11 OUTD DC Output Voltage Representing PRFINA - PRFINB. This output provides a DC voltage proportional to the difference of the input RF powers on RFINA and RFINB. 13, 14 FV2, FV1 Video-Filter Capacitor Inputs for OUTD 15 CSETL Threshold Set Input on Low Comparator 16 COUTL Low-Comparator Output 18, 19 RFINB-, RFINB+ Ground. Connect to the PCB ground plane. Comparator OR Logic Output. Output of COUTH ORed with COUTL. Differential RF Inputs for Detector B. Requires external DC-blocking capacitors. External Capacitor Input. Connecting a capacitor between FB1 and FB2 sets the highpass cutoff frequency corner for detector B (see the Input Highpass Filter section). 21, 22 FB1, FB2 23 OUTB Detector B Output. This output provides a voltage proportional to the log of the input power on differential inputs RFINB+ and RFINB- (RFINB). 24 SETB Set-Point Input for Detector B 25 REF 26 SETA 2V Reference Output Set-Point Input for Detector A 27 OUTA Detector A Output. This output provides a voltage proportional to the log of the input power on differential inputs RFINA+ and RFINA- (RFINA). EP GND Exposed Paddle. EP must connect to the PCB ground plane. Detailed Description The MAX2016 dual logarithmic amplifier is designed for a multitude of applications including dual-channel RF power measurements, AGC control, gain/loss detection, and VSWR monitoring. This device measures RF signals ranging from low frequency to 2.5GHz, and operates from a single 2.7V to 5.25V (using series resistor, R6) power supply. As with its single-channel counterpart (MAX2015), the MAX2016 provides unparalleled performance with a high 80dB dynamic range at 100MHz and exceptional accuracy over the extended temperature and supply voltage ranges. The MAX2016 uses a pair of logarithmic amplifiers to detect and compare the power levels of two RF input signals. The device subtracts one power level from the other to provide a DC output voltage that is proportional 10 to the power difference (gain). The MAX2016 can also measure the return loss/VSWR of an RF signal by monitoring the incident and reflected power levels associated with any given load. A window detector is easily implemented by using the on-chip comparators, OR gate, and 2V reference. This combination of circuitry provides an automatic indication of when the measured gain is outside a programmable range. Alarm monitoring can thus be implemented for detecting high-VSWR states (such as open or shorted loads). RF Inputs (RFINA and RFINB) The MAX2016 has two differential RF inputs. The input to detector A (RFINA) uses the two input ports RFINA+ and RFINA-, and the input to detector B (RFINB) uses the two input ports RFINB+ and RFINB-. ______________________________________________________________________________________ LF-to-2.5GHz Dual Logarithmic Detector/ Controller for Power, Gain, and VSWR Measurements SETA, SETB, and SETD Inputs The SET_ inputs are used for loop control when the device is in controller mode. Likewise, these same SET_ inputs are used to set the slope of the output signal (mV/dB) when the MAX2016 is in detector mode. The center node of the internal resistor-divider is fed to the negative input of the power detector's internal output op amp. The input power level can be determined by the following equation: PRFIN _ = OUTA and OUTB Each OUT_ is a DC voltage proportional to the RF input power level. The change of OUT_ with respect to the power input is approximately 18mV/dB (R1 = R2 = 0). SLOPE + PINT where PINT is the extrapolated intercept point of where the output voltage intersects the horizontal axis. OUTD OUTD is a DC voltage proportional to the difference of the input RF power levels. The change of the OUTD with respect to the power difference is -25mV/dB (R3 = 0). The difference of the input power levels (gain) can be determined by the following equation: (V - VCENTER ) PRFINA - PRFINB = OUTD SLOPE where VCENTER is the output voltage, typically 1V, when PRFINA = PRFINB. Reference The MAX2016 has an on-chip 2V voltage reference. The internal reference output is connected to REF. The output can be used as a reference voltage source for the comparators or other components and can source up to 2mA. VOUT _ Applications Information Monitoring VSWR and Return Loss The MAX2016 can be used to measure the VSWR of an RF signal, which is useful for detecting the presence or absence of a properly loaded termination, such as an antenna (see Figure 1). The transmitted wave from the power amplifier is coupled to RFINA and to the antenna. The reflected wave from the antenna is connected to RFINB through a circulator. When the antenna is missing or damaged, a mismatch in the nominal load VREF CSETL RFINA RFINB COUPLER LOGARITHMIC DETECTOR COUTL COUTL LOGARITHMIC DETECTOR OUTD ATTENUATOR OUTD SETD TRANSMITTER CIRCULATOR MAX2016 20k GND Figure 1. VSWR Monitoring Configuation ______________________________________________________________________________________ 11 MAX2016 The differential RF inputs allow for the measurement of broadband signals ranging from low frequency to 2.5GHz. For single-ended signals, RFINA- and RFINBare AC-coupled to ground. The RF inputs are internally biased and need to be AC-coupled. Using 680pF capacitors, as shown in the Typical Application Circuit, results in a 10MHz highpass corner frequency. An internal 50 resistor between RFINA+ and RFINA- (as well as RFINB+ and RFINB-) produces a good low-frequency to 3.0GHz match. MAX2016 LF-to-2.5GHz Dual Logarithmic Detector/ Controller for Power, Gain, and VSWR Measurements impedance results, leading to an increase in reflected power and subsequent change in the transmission line's VSWR. This increase in reflected power is manifested by an increase in the voltage at OUTD. An alarm condition can be set by using the low comparator output (COUTL) as shown in Figure 1. The comparator automatically senses the change in VSWR, yielding a logic 0 as it compares OUTD to a low DC voltage at CSETL. CSETL, in turn, is set by using the internal reference voltage and an external resistor-divider network. For accurate measurement of signals carrying significant amplitude modulation, limit the bandwidth of the difference amplifier to be less than the lowest modulation frequency. This will minimize the ripple in the OUTD waveform. This is particularly appropriate if the system-level time delay between the two sense points is significant with respect to the period of modulation. Figure 1 illustrates a simple level detector. For windowdetector implementation, see the Comparator/Window Detector section. Measuring VSWR and Return Loss In Figure 2, the two logarithmic amplifiers measure the incident and the reflected power levels to produce two proportional output voltages at OUTA and OUTB. Since OUTD is a DC voltage proportional to the difference of OUTA and OUTB, return loss (RL) and VSWR can be easily calculated within a microprocessor using the following relationships: RL = PRFINA - PRFINB = (VOUTD - VCENTER ) SLOPE where return loss (RL) is expressed in decibels, V CENTER is the output voltage (typically 1V) when P RFINA = P RFINB , and SLOPE is typically equal to -25mV/dB (for R3 = 0). VSWR can similarly be calculated through the following relationship: VSWR = - RL - RL 1 + 10 20 1 - 10 20 RFINA LOGARITHMIC DETECTOR RFINB LOGARITHMIC DETECTOR OUTD ADC SETD MAX2016 20k GND LOAD IN 4-PORT DIRECTIONAL COUPLER Figure 2. Measuring Return Loss and VSWR of a Given Load 12 ______________________________________________________________________________________ P LF-to-2.5GHz Dual Logarithmic Detector/ Controller for Power, Gain, and VSWR Measurements RFINA LOGARITHMIC DETECTOR RFINB LOGARITHMIC DETECTOR MAX2016 MAX2016 20k SETD OUTD OUTD GND RF BLOCK COUPLER COUPLER OUT IN Figure 3. Gain Measurement Configuration Measuring Gain The MAX2016 can be used to measure the gain of an RF block (or combination of blocks) through the implementation outlined in Figure 3. As shown, a coupled signal from the input of the block is fed into RFINA, while the coupled output is connected to RFINB. The DC output voltage at OUTD is proportional to the power difference (i.e., gain). The gain of a complete receiver or transmitter lineup can likewise be measured since the MAX2016 accepts RF signals that range from low frequency to 2.5GHz; see Figure 4. The MAX2016 accurately measures the gain, regardless of the different frequencies present within superheterodyne architectures. For accurate measurement of signals carrying significant amplitude modulation, limit the bandwidth of the difference amplifier to be less than the lowest modulation frequency. This will minimize the ripple in the OUTD waveform. This is particularly appropriate if the system-level time delay between the two sense points is significant with respect to the period of modulation. MIXER fIF fRF COUPLER COUPLER LNA LO LOGARITHMIC RFINB DETECTOR RFINA LOGARITHMIC DETECTOR OUTD OUT MAX2016 SETD 20k Figure 4. Conversion Gain Measurement Configuration ______________________________________________________________________________________ 13 MAX2016 LF-to-2.5GHz Dual Logarithmic Detector/ Controller for Power, Gain, and VSWR Measurements Measuring Power (RSSI Detector Mode) In detector mode, the MAX2016 acts like a receive-signal-strength indicator (RSSI), which provides an output voltage proportional to the input power. This is accomplished by providing a feedback path from OUTA (OUTB) to SETA (SETB) (R1/R2 = 0; see Figure 5). By connecting SET_ directly to OUT_, the op-amp gain is set to 2V/V due to two internal 20k feedback resistors. This provides a detector slope of approximately 18mV/dB with a 0.5V to 1.8V output range. Gain-Controller Mode The MAX2016 can be used as a gain controller within an automatic gain-control (AGC) loop. As shown in Figure 6, RFINA and RFINB monitor the VGA's input and output power levels, respectively. The MAX2016 produces a DC voltage at OUTD that is proportional to the difference in these two RF input power levels. An internal op amp compares the DC voltage with a reference voltage at SETD. The op amp increases or decreases the voltage at OUTD until OUTD equals SETD. Thus, the MAX2016 adjusts the gain of the VGA to a level determined by the voltage applied to SETD. Place the nominal signal levels of RFINA and RFINB near the middle of their respective dynamic ranges to accommodate the largest range of gain compensation. This is nominally -25dBm to -30dBm. If so selected, the nominal voltage applied to SETD will be approximately 1.0V. Operate the SETD voltage within the range of 0.5V to 1.5V for the greatest accuracy of gain control. VGA DETECTORS OUTA IN_ OUTA RFIN+A VGA OUTPUT VGA INPUT COUPLER COUPLER 20k SETA GAIN CONTROL INPUT R1/R2 SET-POINT DAC RFIN-A 20k SETD OUTD GND MAX2016 DETECTORS MAX2016 OUTB IN_ OUTB 20k RFIN+B 20k SETB R1/R2 RFIN-B RFINA 20k Figure 5. In Detector Mode (RSSI), OUTA/OUTB is a DC Voltage Proportional to the Input Power 14 LOGARITHMIC DETECTOR LOGARITHMIC DETECTOR RFINB Figure 6. In Gain-Controller Mode, the OUTD Maintains the Gain of the VGA ______________________________________________________________________________________ LF-to-2.5GHz Dual Logarithmic Detector/ Controller for Power, Gain, and VSWR Measurements OUTA and OUTB Slope Adjustment The transfer slope function of OUTA and OUTB can be increased from its nominal value by varying resistors R1 and R2 (see the Typical Application Circuit). The equation controlling the slope is: mV SLOPE OUTA OR OUTB = 9 dB (R1 or R2) + 40k 20k OUTD Slope Adjustment The transfer slope function of OUTD can be increased from its nominal value by varying resistor R3 (see the Typical Application Circuit). The equation controlling the slope is: mV R3 + 20k SLOPE OUTD = -25 dB 20k Input Highpass Filters POWER AMPLIFIER TRANSMITTER COUPLER GAIN-CONTROL INPUT LOWPASS FILTER RFINA/ LOGARITHMIC RFINB DETECTOR OUTA/ OUTB SET-POINT DAC The MAX2016 integrates a programmable highpass filter on each RF input. The lower cutoff frequency of the MAX2016 can be decreased by increasing the external capacitor value between FA1 and FA2 or FB1 and FB2. By default, with no capacitor connecting FA1 and FA2 or FB1 and FB2, the lower cutoff frequency is 20MHz. Using the following equation determines the lowest operating frequency: frequency = 1 2RC where R = 2. SETA/ SETB Differential Output Video Filter 20k 20k MAX2016 The bandwidth and response time difference of the output amplifier can be controlled with the external capacitor, C15, connected between FV1 and FV2. With no external capacitor, the bandwidth is greater than 20MHz. The following equation determines the bandwidth of the amplifier difference: frequency = Figure 7. In Power-Controller Mode, the DC Voltage at OUTA or OUTB Controls the Gain of the PA, Leading to a Constant Output Power Level (Note: Only one controller channel is shown within the figure. Since the MAX2016 is a dual controller/detector, the second channel can be easily implemented by using the adjacent set of input and output connections.) 1 2RC where R = 1.8k. Use a video bandwidth lower than the anticipated lowest amplitude-modulation frequency range to yield the greatest accuracy in tracking the average carrier power for high peak-to-average ratio waveforms. ______________________________________________________________________________________ 15 MAX2016 Power-Controller Mode The MAX2016 can also be used as a power detector/ controller within an AGC loop. Figure 7 depicts a scenario where the MAX2016 is employed as the AGC circuit. As shown in the figure, the MAX2016 monitors the output of the PA through a directional coupler. An internal differencing amplifier (Figure 5) compares the detected signal with a reference voltage determined by VSET_. The differencing amplifier increases or decreases the voltage at OUT_, according to how closely the detected signal level matches the VSET_ reference. The MAX2016 maintains the power of the PA to a level determined by the voltage applied to SET_. Since the logarithmic detector responds to any amplitude modulation being carried by the carrier signal, it may be necessary to insert an external lowpass filter between the differencing amplifier output (OUTA/OUTB) and the gain-control element to remove this modulation signal. MAX2016 LF-to-2.5GHz Dual Logarithmic Detector/ Controller for Power, Gain, and VSWR Measurements CSETH MAX2016 COR RFINA LOGARITHMIC DETECTOR CSETL RFINB LOGARITHMIC DETECTOR OUTD SETD 20k RF BLOCK COUPLER IN COUPLER OUT Figure 8. Window Comparators Monitoring Mode. COR goes high if OUTD drops below CSETL or rises above CSETH. Comparators/Window Detectors The MAX2016 integrates two comparators for use in monitoring the difference in power levels (gain) of RFINA and RFINB. The thresholds of the two comparators are set to the voltage applied to the CSETL and CSETH pins. The output of each comparator can be monitored independently or from the COR output that ORs the outputs of the individual comparators. This can be used for a window-detector function. These comparators can be used to trigger hardware interrupts, allowing rapid detection of over-range conditions. These comparators are high-speed devices. Connect high-value bypass capacitors (0.1F) between each comparator threshold input (CSETL and CSETH) to ground to provide a solid threshold voltage at high switching speeds. Some applications may benefit from the use of hysteresis in the comparator response. This can be useful for prevention of false triggering in the presence of small noise perturbations in the signal levels, or with signals with large amplitude modulation. To introduce hysteresis into the comparator output, connect a feedback resistor from COUTL to CSTEL. Select the value of this resistor, in combination with the resistive-divider values used to set threshold-level CSETL, to set the amount of hysteresis. Set the parallel combination of resistors connected to CSETL to be less than 10k for best performance. 16 Figure 8 illustrates the use of these comparators in a gain-monitoring application. The low comparator has its threshold (CSETL) set at a low-gain trip point. If the gain drops below this trip point, the COUTL output goes from a logic 0 to a logic 1. The high comparator has its threshold (CSETH) set at a high trip point. If the gain exceeds this trip point, the COUTH output goes from logic 0 to logic 1. The window comparator output (COR) rests a logic 0 if the gain is in the acceptable range, between CSETL and CSETH. It goes to a logic 1 if the gain is either above or below these limits. Power-Supply Connection The MAX2016 is designed to operate from a single +2.7V to +3.6V supply. To operate under a higher supply voltage range, a resistor must be connected in series with the power supply and VCC to reduce the voltage delivered to the chip. For a +4.75V to +5.25V supply, use a 37.4 (1%) resistor in series with the supply. Layout Considerations A properly designed PCB 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 PCB exposed pad MUST be connected to the ground plane of the PCB. It is suggested that multiple vias be used to connect this pad to the lower level ground ______________________________________________________________________________________ LF-to-2.5GHz Dual Logarithmic Detector/ Controller for Power, Gain, and VSWR Measurements Exposed Pad RF/Thermal Considerations The exposed paddle (EP) of the MAX2016's 28-pin thin QFN-EP package provides two functions. One is a low thermal-resistance path to the die; the second is a lowRF impedance ground connection. The EP MUST be soldered to a ground plane on the PCB, either directly or through an array of plated via holes (minimum of four holes to provide ground integrity). Power-Supply Bypassing Proper voltage-supply bypassing is essential for highfrequency circuit stability. Bypass each VCC pin with a capacitor as close to the pin as possible (Typical Application Circuit). Functional Diagram 2, 9, 12, 20 26 SETA 25 REF 23 OUTB 24 SETB VCC 20k 5, 17 27 OUTA 2.0V REF 20k 20k 20k GND 3 RFINA+ RFINB+ 19 LOG AMPLIFIERS 50 LOG AMPLIFIERS 50 4 RFINA- RFINB- 18 EXPOSED PAD 1 FA1 FB1 21 28 FA2 FB2 22 MAX2016 FV1 14 FV2 13 8 20k COR CSETH 7 COUTH 6 COUTL 16 CSETL 15 OUTD SETD 11 10 ______________________________________________________________________________________ 17 MAX2016 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 PCB. The MAX2016 Evaluation Kit can be used as a reference for board layout. Gerber files are available upon request at www.maxim-ic.com. LF-to-2.5GHz Dual Logarithmic Detector/ Controller for Power, Gain, and VSWR Measurements MAX2016 Typical Application Circuit VREF VOUTA VOUTB VCC R6 R1 R2 VCC C5 COMPARATORA 7 VCC FB2 OUTB REF SETB SETA 22 RFINB+ MAX2016 RFINA- RFINB- GND GND EXPOSED PADDLE COUTH COUTL CSETH C16 CSETL 8 9 10 11 12 13 21 C10 C11 20 19 C8 RFINB 18 C9 17 16 COMPARATORB 15 VCC C17 FV1 6 RFINA+ FV2 5 23 VCC VCC C2 24 VCC OUTD 4 25 FB1 SETD 3 RFINA OUTA FA2 2 C1 26 FA1 VCC 1 COR C3 27 C18 VCC C12 28 C4 VS 14 C15 A+B VCC C7 VCC C6 C13 C14 R3 NOTE: COMPARATORS ARE DISABLED BY CONNECTING CSETL AND CSETH TO VCC. VOUTD Table 1. Component Values Used in the Typical Application Circuit DESIGNATION VALUE DESCRIPTION C1, C2, C8, C9 680pF Microwave capacitors (0402) C3, C6, C10, C13 33pF Microwave capacitors (0402) C4, C7, C11, C14 0.1F Microwave capacitors (0603) C5, C12, C15, C16, C17 Not used C18 10F R1, R2, R3 0 R6 0 37.4 Capacitors are optional for frequency compensation, bypass Tantalum capacitor (C case) Resistors (0402) Resistor (1206) for VS = 2.7V to 3.6V 1% resistor (1206) for VS = 4.75V to 5.25V Chip Information PROCESS: BiCMOS 18 ______________________________________________________________________________________ LF-to-2.5GHz Dual Logarithmic Detector/ Controller for Power, Gain, and VSWR Measurements QFN THIN.EPS ______________________________________________________________________________________ 19 MAX2016 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) Revision History Pages changed at Rev 1: 1, 5, 10-20 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. 20 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2006 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc. MAX2016 MAX2016 LF-to-2.5GHz Dual Logarithmic Detector/ Controller for Power, Gain, and VSWR Measurements