MAX2016ETI+D - Maxim Integrated

General Description

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 sig-

nals 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 pro-

portional 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 -40°C

to +85°C 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

Cellular Base Station, Microwave Link, Radar,

and other Military Applications

RF/IF Power Amplifier (PA) Linearization

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.

MAX2016

LF-to-2.5GHz Dual Logarithmic Detector/

Controller for Power, Gain, and VSWR Measurements

________________________________________________________________ Maxim Integrated Products 1

FA1 1

VCC 2

RFINA+ 3

RFINA- 4

GND 5

COUTH 6

CSETH 7

FB121

VCC

RFINB+19

RFINB-18

GND17

COUTL16

CSETL15

COR

VCC

SETD

OUTD

VCC

FV2

FV1

FA2

OUTA

SETA

REF

SETB

OUTB

FB2

MAX2016

THIN QFN

Pin Configuration

Ordering Information

19-3404; Rev 1; 10/06

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.

EVALUATION KIT

AVAILABLE

PART TEMP RANGE PIN-

PACKAGE

PKG

CODE

MAX2016ETI -40°C to +85°C28 Thi n QFN - E P *,

b ul kT2855-3

MAX2016ETI-T -40°C to +85°C28 Thi n QFN - E P *,

T/R T2855-3

MAX2016ETI+D -40°C to +85°C28 Thi n QFN - E P *,

l ead fr ee, b ul kT2855-3

MAX2016ETI+TD -40°C to +85°C28 Thi n QFN - E P *,

l ead fr ee, T/R T2855-3

*EP = Exposed pad.

+Indicates lead-free package.

D= Dry pack.

Typical Application Circuit appears at end of data sheet.

MAX2016

LF-to-2.5GHz Dual Logarithmic Detector/

Controller for Power, Gain, and VSWR Measurements

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

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.

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= +70°C)

28-Pin, 5mm x 5mm Thin QFN (derate 35.7mW/°C

above +70°C)..................................................................2.8W

Operating Temperature Range ...........................-40°C to +85°C

Junction Temperature......................................................+150°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

DC ELECTRICAL CHARACTERISTICS

(VCC = +2.7V to +3.6V, R1= R2= R3= 0Ω, TA= -40°C to +85°C, unless otherwise noted. Typical values are at VCC = +3.3V,

CSETL = CSETH = VCC, 50ΩRF system, TA= +25°C, unless otherwise noted.) (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

POWER SUPPLY

VSR6 = 0Ω2.7 3.3 3.6

Supply Voltage VSR6 = 37.4Ω4.75 5 5.25 V

Total Supply Current ICC 43 55 mA

Measured in each pin 2 and pin 20 16

Measured in pin 9 2

Supply Current

Measured in pin 12 9

INPUT INTERFACE

Input Impedance Differential impedance at RFINA and RFINB 50 Ω

Resistance at SETD 20

Input Resistance R Resistance at SETA and SETB 40 kΩ

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

OUTD Accuracy ±12 mV

COMPARATORS

Output High Voltage VOH RLOAD ≥ 10kΩVCC -

10mV V

Output Low Voltage VOL RLOAD ≥ 10kΩ10 mV

Input Voltage Measured at CSETL and CSETH GND to

VCC V

Input Bias Current CSETL and CSETH 1 nA

REFERENCE

Output Voltage on Pin 25 RLOAD ≥ 2kΩ2V

Load Regulation Source 2mA -5 mV

MAX2016

LF-to-2.5GHz Dual Logarithmic Detector/

Controller for Power, Gain, and VSWR Measurements

_______________________________________________________________________________________ 3

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

RF Input Frequency Range fRF AC-coupled input 2.5 GHz

Return Loss S11 0.1GHz to 3GHz 20 dB

Large-Signal Response Time PRFIN = no signal to 0dBm, ±0.5dB settling

accuracy 100 ns

RSSI MODE—0.1GHz

RF Input Power Range (Note 2) -70 to

+10 dBm

±3dB Dynamic Range TA = -20°C to +85°C (Note 3) 80 dB

Range Center -32 dBm

TA = +25°C to +85°C +0.0083

Temperature Sensitivity PRFINA = PRFINB =

-32dBm TA = +25°C to -20°C -0.0083 dB/°C

Slope (Note 4) 19 mV/dB

Typical Slope Variation TA = -20°C to +85°C -4 µV/°C

Intercept (Note 5) -100 dBm

Typical Intercept Variation TA = -20°C to +85°C 0.03 dBm/°C

RSSI MODE—0.9GHz

RF Input Power Range (Note 2) -70 to

+10 dBm

±3dB Dynamic Range TA = -20°C to +85°C (Note 3) 80 dB

Range Center -30 dBm

TA = +25°C to +85°C +0.0083

Temperature Sensitivity PRFINA = PRFINB =

-30dBm TA = +25°C to -20°C -0.0083 dB/°C

Slope (Note 4) 18.1 mV/dB

Typical Slope Variation TA = -20°C to +85°C -4 µV/°C

Intercept (Note 5) -97 dBm

Typical Intercept Variation TA = -20°C to +85°C 0.02 dBm/°C

RSSI MODE—1.9GHz

RF Input Power Range (Note 2) -55 to

+12 dBm

±3dB Dynamic Range TA = -20°C to +85°C (Note 3) 67 dB

Range Center -27 dBm

TA = +25°C to +85°C +0.0125

Temperature Sensitivity PRFINA = PRFINB =

-27dBm TA = +25°C to -20°C -0.0125 dB/°C

Slope (Note 4) 18 mV/dB

Typical Slope Variation TA = -20°C to +85°C -4.8 µV/°C

Intercept (Note 5) -88 dBm

Typical Intercept Variation TA = -20°C to +85°C 0.03 dBm/°C

AC ELECTRICAL CHARACTERISTICS—OUTA AND OUTB

(Typical Application Circuit, VCC = +2.7V to +3.3V, R1= R2= R3= 0Ω, TA= -40°C to +85°C, unless otherwise noted. Typical values

are at VCC = 3.3V, CSETL = CSETH = VCC, TA= +25°C, unless otherwise noted.) (Note 1)

MAX2016

LF-to-2.5GHz Dual Logarithmic Detector/

Controller for Power, Gain, and VSWR Measurements

4 _______________________________________________________________________________________

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

RSSI MODE—2.17GHz

RF Input Power Range (Note 2) -52 to

+12 dBm

±3dB Dynamic Range TA = -20°C to +85°C (Note 3) 64 dB

Range Center -25 dBm

TA = +25°C to +85°C +0.0135

Temperature Sensitivity PRFINA = PRFINB =

-25dBm TA = +25°C to -20°C -0.0135 dB/°C

Slope (Note 4) 17.8 mV/dB

Typical Slope Variation TA = -20°C to +85°C -8 µV/°C

Intercept (Note 5) -81 dBm

Typical Intercept Variation TA = -20°C to +85°C 0.03 dBm/°C

RSSI MODE—2.5GHz

RF Input Power Range (Note 2) -45 to

+7 dBm

±3dB Dynamic Range TA = -20°C to +85°C (Note 3) 52 dB

Range Center -23 dBm

TA = +25°C to +85°C +0.0167

Temperature Sensitivity PRFINA = PRFINB =

-23dBm TA = +25°C to -20°C -0.0167 dB/°C

Slope (Note 4) 17.8 mV/dB

Typical Slope Variation TA = -20°C to +85°C -8 µV/°C

Intercept (Note 5) -80 dBm

Typical Intercept Variation TA = -20°C to +85°C 0.03 dBm/°C

AC ELECTRICAL CHARACTERISTICS—OUTA AND OUTB (continued)

(Typical Application Circuit, VCC = +2.7V to +3.3V, R1= R2= R3= 0Ω, TA= -40°C to +85°C, unless otherwise noted. Typical values

are at VCC = 3.3V, CSETL = CSETH = VCC, TA= +25°C, unless otherwise noted.) (Note 1)

AC ELECTRICAL CHARACTERISTICS—OUTD

(Typical Application Circuit, VCC = +2.7V to +3.3V, R1= R2= R3= 0Ω, TA= -40°C to +85°C, unless otherwise noted. Typical values

are at VCC = 3.3V, CSETL = CSETH = VCC, TA= +25°C, unless otherwise noted.) (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

OUTD Center Point PRFINA = PRFINB 1V

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

MAX2016

LF-to-2.5GHz Dual Logarithmic Detector/

Controller for Power, Gain, and VSWR Measurements

_______________________________________________________________________________________ 5

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Large-Signal Rise and Fall Time Any 30dB step, no external capacitor on

pins FV1 and FV2 35 ns

0.1GHz PRFINB = -32dBm 80

0.9GHz PRFINB = -30dBm 75

1.9GHz PRFINB = -27dBm 60

2.17GHz PRFINB = -25dBm 55

±1dB Dynamic Range

2.5GHz PRFINB = -23dBm 50

Slope fRF = 0.1GHz to 2.5GHz (A-B) -25 mV/dB

OUTD Voltage Deviation PRFINA = PRFINB = -30dBm, TA =

-20°C to +85°C ±0.25 dB

0.1GHz, PRFINB =

-32dBm 80

0.9GHz, PRFINB =

-30dBm 70

1.9GHz, PRFINB =

-27dBm 55

2.17GHz, PRFINB =

-25dBm 50

±1dB Dynamic Range over

Temperature Relative to Best-Fit

Curve at +25°C

PRFINA is swept ;

TA = -20°C to

+85°C

2.5GHz, PRFINB =

-23dBm 45

Gain Measurement Balance PRFINB = PRFINB = -50dBm to -5dBm, fRF =

1.9GHz 0.2 dB

0.9GHz 90

1.9GHz 65

Channel Isolation

2.5GHz 55

AC ELECTRICAL CHARACTERISTICS—OUTD (continued)

(Typical Application Circuit, VCC = +2.7V to +3.3V, R1= R2= R3= 0Ω, TA= -40°C to +85°C, unless otherwise noted. Typical values

are at VCC = 3.3V, CSETL = CSETH = VCC, TA= +25°C, unless otherwise noted.) (Note 1)

Note 1: The MAX2016 is tested at TA= +25°C and is guaranteed by design for TA= -40°C to +85°C.

Note 2: Typical minimum and maximum range of the detector at the stated frequency.

Note 3: Dynamic range refers to the range over which the error remains within the ±3dB range.

Note 4: 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 calcu-

lated by fitting a root-mean-square straight line to the data.

MAX2016

LF-to-2.5GHz Dual Logarithmic Detector/

Controller for Power, Gain, and VSWR Measurements

6 _______________________________________________________________________________________

Typical Operating Characteristics

(MAX2016 EV kit, VCC = 3.3V, R1= R2= R3= 0Ω, CSETL = CSETH = VCC, TA= +25°C, unless otherwise noted.)

DIFFERENTIAL OUTPUT VOLTAGE

vs. A/B DIFFERENCE

MAX2016 toc01

MAGNITUDE RATIO (dB)

VOUTD (V)

3010-10-30

0.5

1.0

1.5

2.0

2.5

-50 50

fIN = 100MHz

PRFINB = -32dBm PRFINA IS SWEPT

TA = -20°C,

+25°C, +85°C

DIFFERENTIAL OUTPUT-VOLTAGE ERROR

vs. A/B DIFFERENCE

MAX2016 toc02

MAGNITUDE RATIO (dB)

ERROR (dB)

3010-10-30

-2

-1

-3

-50 50

fIN = 100MHz

PRFINB = -32dBm

NORMALIZED TO DATA

AT +25°C

TA = -20°C

TA = +85°C

DIFFERENTIAL OUTPUT VOLTAGE

vs. A/B DIFFERENCE

MAX2016 toc03

MAGNITUDE RATIO (dB)

VOUTD (V)

3010-10-30

0.5

1.0

1.5

2.0

2.5

-50 50

fIN = 900MHz

PRFINB = -30dBm PRFINA IS SWEPT

TA = -20°C,

+25°C, +85°C

DIFFERENTIAL OUTPUT-VOLTAGE ERROR

vs. A/B DIFFERENCE

MAX2016 toc04

MAGNITUDE RATIO (dB)

ERROR (dB)

3010-10-30

-2

-1

-3

-50 50

fIN = 900MHz

PRFINB = -30dBm

NORMALIZED TO DATA

AT +25°C

TA = -20°C

TA = +85°C

DIFFERENTIAL OUTPUT VOLTAGE

vs. A/B DIFFERENCE

MAX2016 toc05

MAGNITUDE RATIO (dB)

VOUTD (V)

200-20

0.5

1.0

1.5

2.0

2.5

-40 40

fIN = 1900MHz

PRFINB = -27dBm

PRFINA IS SWEPT

TA = -20°C

TA = +25°C

TA = +85°C

DIFFERENTIAL OUTPUT-VOLTAGE ERROR

vs. A/B DIFFERENCE

MAX2016 toc06

MAGNITUDE RATIO (dB)

ERROR (dB)

200-20

-2

-1

-3

-40 40

fIN = 1900MHz

PRFINB = -27dBm

NORMALIZED TO DATA

AT +25°C

TA = -20°C

TA = +85°C

MAX2016

LF-to-2.5GHz Dual Logarithmic Detector/

Controller for Power, Gain, and VSWR Measurements

_______________________________________________________________________________________ 7

Typical Operating Characteristics (continued)

(MAX2016 EV kit, VCC = 3.3V, R1= R2= R3= 0Ω, CSETL = CSETH = VCC, TA= +25°C, unless otherwise noted.)

DIFFERENTIAL OUTPUT-VOLTAGE BALANCE

MAX2016 toc11

PRFINA (dBm)

VOUTD (V)

-15-30-45

0.90

0.95

1.00

1.05

1.10

1.15

0.85

-60 0

fIN = 1900MHz

PRFINA = PRFINB + 5dB

PRFINA = PRFINB - 5dB

PRFINA = PRFINB

TA = -20°C

TA = +25°C

TA = +85°C

TA = -20°C

TA = +25°CTA = +85°C

TA = -20°C

TA = +25°C

TA = +85°C

S11 MAGNITUDE

MAX2016 toc12

FREQUENCY (GHz)

MAGNITUDE (dB)

2.52.01.51.00.5

-55

-50

-45

-40

-35

-30

-25

-20

-15

-10

-60

03.0

TA = -20°C

TA = +25°C

TA = +85°C

200-20-40 40

MAX2016 toc09

DIFFERENTIAL OUTPUT VOLTAGE

vs. A/B DIFFERENCE

MAGNITUDE RATIO (dB)

VOUTD (V)

0.5

1.0

1.5

2.0

2.5

fIN = 2500MHz

PRFINB = -23dBm PRFINA IS SWEPT

TA = -20°C

TA = +25°C

TA = +85°C

DIFFERENTIAL OUTPUT-VOLTAGE ERROR

vs. A/B DIFFERENCE

MAX2016 toc10

MAGNITUDE RATIO (dB)

ERROR (dB)

200-20

-2

-1

-3

-40 40

fIN = 2500MHz

PRFINB = -23dBm

NORMALIZED TO DATA

AT +25°C

TA = -20°C

TA = +85°C

15-5-25-45 35

MAX2016 toc07

DIFFERENTIAL OUTPUT VOLTAGE

vs. A/B DIFFERENCE

MAGNITUDE RATIO (dB)

VOUTD (V)

0.5

1.0

1.5

2.0

2.5

fIN = 2170MHz

PRFINB = -25dBm PRFINA IS SWEPT

TA = -20°C

TA = +25°C

TA = +85°C

DIFFERENTIAL OUTPUT-VOLTAGE ERROR

vs. A/B DIFFERENCE

MAX2016 toc08

MAGNITUDE RATIO (dB)

ERROR (dB)

200-20

-2

-1

-3

-40 40

fIN = 2170MHz

PRFINB = -25dBm

NORMALIZED TO DATA

AT +25°C

TA = -20°C

TA = +85°C

MAX2016

LF-to-2.5GHz Dual Logarithmic Detector/

Controller for Power, Gain, and VSWR Measurements

8 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(MAX2016 EV kit, VCC = 3.3V, R1= R2= R3= 0Ω, CSETL = CSETH = VCC, TA= +25°C, unless otherwise noted.)

VOUTA vs. PRFINA

MAX2016 toc17

PRFINA (dBm)

VOUTA (V)

-5-25-45

0.5

1.0

1.5

2.0

2.5

-65 15

fIN = 1900MHz TA = -20°C

TA = +25°C

TA = +85°C

VOUTA ERROR vs. PRFINA

MAX2016 toc18

PRFINA (dBm)

ERROR (dB)

-5-25-45

-2

-1

-3

-65 15

fIN = 1900MHz

NORMALIZED TO DATA

AT +25°C

TA = -20°C

TA = +85°C

VOUTA vs. PRFINA

MAX2016 toc13

PRFINA (dBm)

VOUTA (V)

0-20-40-60

0.5

1.0

1.5

2.0

2.5

-80 20

fIN = 100MHz TA = -20°C

TA = +25°C

TA = +85°C

VOUTA ERROR vs. PRFINA

MAX2016 toc14

PRFINA (dBm)

ERROR (dB)

0-20-40-60

-2

-1

-3

-80 20

fIN = 100MHz

NORMALIZED TO DATA

AT +25°C

TA = -20°C

TA = +85°C

VOUTA vs. PRFINA

MAX2016 toc15

PRFINA (dBm)

VOUTA (V)

0-20-40-60

0.5

1.0

1.5

2.0

2.5

-80 20

fIN = 900MHz

TA = -20°C

TA = +25°C

TA = +85°C

VOUTA ERROR vs. PRFINA

MAX2016 toc16

PRFINA (dBm)

ERROR (dB)

0-15-30-45-60

-2

-1

-3

-75 15

fIN = 900MHz

NORMALIZED TO DATA

AT +25°C

TA = -20°C

TA = +85°C

MAX2016

LF-to-2.5GHz Dual Logarithmic Detector/

Controller for Power, Gain, and VSWR Measurements

_______________________________________________________________________________________ 9

Typical Operating Characteristics (continued)

(MAX2016 EV kit, VCC = 3.3V, R1= R2= R3= 0Ω, CSETL = CSETH = VCC, TA= +25°C, unless otherwise noted.)

VOUTA vs. PRFINA

MAX2016 toc19

PRFINA (dBm)

VOUTA (V)

0-15-30-45

0.5

1.0

1.5

2.0

2.5

-60 15

fIN = 2170MHz

TA = -20°C

TA = +25°C

TA = +85°C

VOUTA ERROR vs. PRFINA

MAX2016 toc20

PRFINA (dBm)

ERROR (dB)

0-15-30-45

-2

-1

-3

-60 15

fIN = 2170MHz

NORMALIZED TO DATA

AT +25°C

TA = -20°C

TA = +85°C

MAX2016 toc21

0-15-30-45

0.5

1.0

1.5

2.0

2.5

-60 15

VOUTA vs. PRFINA

PRFINA (dBm)

VOUTA (V)

fIN = 2500MHz

TA = -20°C

TA = +25°C

TA = +85°C

-2

-1

-3

MAX2016 toc22

0-15-30-45-60 15

VOUTA ERROR vs. PRFINA

PRFINA (dBm)

ERROR (dB)

fIN = 2500MHz

NORMALIZED TO DATA

AT +25°C

TA = -20°C

TA = +85°C

MAX2016

LF-to-2.5GHz Dual Logarithmic Detector/

Controller for Power, Gain, and VSWR Measurements

10 ______________________________________________________________________________________

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 perfor-

mance 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

to the power difference (gain). The MAX2016 can also

measure the return loss/VSWR of an RF signal by moni-

toring the incident and reflected power levels associat-

ed 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 indica-

tion of when the measured gain is outside a program-

mable range. Alarm monitoring can thus be imple-

mented 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-.

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- Differential RF Inputs for Detector A. Requires external DC-blocking capacitors.

5, 17 GND Ground. Connect to the PCB ground plane.

6 COUTH High-Comparator Output

7 CSETH Threshold Input on High Comparator

8 COR Comparator OR Logic Output. Output of COUTH ORed with COUTL.

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+ Differential RF Inputs for Detector B. Requires external DC-blocking capacitors.

21, 22 FB1, FB2 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).

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 2V Reference Output

26 SETA 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.

MAX2016

LF-to-2.5GHz Dual Logarithmic Detector/

Controller for Power, Gain, and VSWR Measurements

______________________________________________________________________________________ 11

The differential RF inputs allow for the measurement of

broadband signals ranging from low frequency to

2.5GHz. For single-ended signals, RFINA- and RFINB-

are 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 50Ωresistor between RFINA+ and RFINA- (as

well as RFINB+ and RFINB-) produces a good low-fre-

quency to 3.0GHz match.

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 sig-

nal (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 out-

put op amp.

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.

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= 0Ω).

The input power level can be determined by the following

equation:

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 =

0Ω). The difference of the input power levels (gain) can

be determined by the following equation:

where VCENTER is the output voltage, typically 1V, when

PRFINA = PRFINB.

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 anten-

na. 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

PP VV

SLOPE

RFINA RFINB OUTD CENTER

−=−()

SLOPE P

RFIN OUT INT__

MAX2016

CSETL

COUTL

VREF

LOGARITHMIC

DETECTOR

LOGARITHMIC

DETECTOR

COUTL

OUTD

SETD

20kΩ

RFINB

RFINA

OUTD

TRANSMITTER

COUPLER

CIRCULATOR

ATTENUATOR

GND

Figure 1. VSWR Monitoring Configuation

MAX2016

LF-to-2.5GHz Dual Logarithmic Detector/

Controller for Power, Gain, and VSWR Measurements

12 ______________________________________________________________________________________

impedance results, leading to an increase in reflected

power and subsequent change in the transmission

line’s VSWR. This increase in reflected power is mani-

fested by an increase in the voltage at OUTD. An alarm

condition can be set by using the low comparator out-

put (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 refer-

ence voltage and an external resistor-divider network.

For accurate measurement of signals carrying signifi-

cant amplitude modulation, limit the bandwidth of the

difference amplifier to be less than the lowest modula-

tion 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 window-

detector 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:

where return loss (RL) is expressed in decibels,

VCENTER is the output voltage (typically 1V) when

PRFINA = PRFINB, and SLOPE is typically equal to

-25mV/dB (for R3 = 0Ω).

VSWR can similarly be calculated through the following

relationship:

VSWR

−

⎛

⎝⎞

⎠

⎛

⎝⎞

⎠

110

RL P P VV

SLOPE

RFINA RFINB OUTD CENTER

=− = −

()

MAX2016

RFINA

RFINB

GND

ADC μP

IN LOAD

4-PORT DIRECTIONAL

COUPLER

LOGARITHMIC

DETECTOR

LOGARITHMIC

DETECTOR

OUTD

SETD

20kΩ

Figure 2. Measuring Return Loss and VSWR of a Given Load

MAX2016

LF-to-2.5GHz Dual Logarithmic Detector/

Controller for Power, Gain, and VSWR Measurements

______________________________________________________________________________________ 13

Measuring Gain

The MAX2016 can be used to measure the gain of an

RF block (or combination of blocks) through the imple-

mentation 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 signifi-

cant amplitude modulation, limit the bandwidth of the

difference amplifier to be less than the lowest modula-

tion 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.

MAX2016

RFINA

RFINB

LOGARITHMIC

DETECTOR

LOGARITHMIC

DETECTOR

GND

OUTD

SETD

20kΩ

COUPLER COUPLER

RF BLOCK

OUT

OUTD

Figure 3. Gain Measurement Configuration

MAX2016

LNA

fRF fIF

RFINA RFINB

LOGARITHMIC

DETECTOR

LOGARITHMIC

DETECTOR

COUPLER

MIXER

COUPLER

OUTD

SETD

20kΩ

OUT

Figure 4. Conversion Gain Measurement Configuration

MAX2016

LF-to-2.5GHz Dual Logarithmic Detector/

Controller for Power, Gain, and VSWR Measurements

14 ______________________________________________________________________________________

Measuring Power (RSSI Detector Mode)

In detector mode, the MAX2016 acts like a receive-sig-

nal-strength indicator (RSSI), which provides an output

voltage proportional to the input power. This is accom-

plished by providing a feedback path from OUTA

(OUTB) to SETA (SETB) (R1/R2 = 0Ω; see Figure 5).

By connecting SET_ directly to OUT_, the op-amp gain

is set to 2V/V due to two internal 20kΩfeedback resis-

tors. 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 refer-

ence 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.

MAX2016

RFIN+A

RFIN-A

OUTA

IN_

GND

R1/R2

20kΩ

DETECTORS

SETA

OUTA

RFIN+B

RFIN-B

OUTB

IN_

R1/R2

20kΩ

DETECTORS

SETB

OUTB

Figure 5. In Detector Mode (RSSI), OUTA/OUTB is a DC

Voltage Proportional to the Input Power

MAX2016

LOGARITHMIC

DETECTOR

LOGARITHMIC

DETECTOR

20kΩ

VGA

GAIN CONTROL INPUT

RFINA RFINB

OUTDSETD

VGA INPUT VGA OUTPUT

SET-POINT

DAC

COUPLER COUPLER

Figure 6. In Gain-Controller Mode, the OUTD Maintains the

Gain of the VGA

MAX2016

LF-to-2.5GHz Dual Logarithmic Detector/

Controller for Power, Gain, and VSWR Measurements

______________________________________________________________________________________ 15

Power-Controller Mode

The MAX2016 can also be used as a power detector/

controller within an AGC loop. Figure 7 depicts a sce-

nario where the MAX2016 is employed as the AGC cir-

cuit. As shown in the figure, the MAX2016 monitors the

output of the PA through a directional coupler. An inter-

nal differencing amplifier (Figure 5) compares the

detected signal with a reference voltage determined by

VSET_. The differencing amplifier increases or decreas-

es 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 ampli-

tude 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.

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:

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:

Input Highpass Filters

The MAX2016 integrates a programmable highpass fil-

ter 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:

where R = 2Ω.

Differential Output Video Filter

The bandwidth and response time difference of the out-

put amplifier can be controlled with the external capaci-

tor, 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:

where R = 1.8kΩ.

Use a video bandwidth lower than the anticipated low-

est amplitude-modulation frequency range to yield the

greatest accuracy in tracking the average carrier

power for high peak-to-average ratio waveforms.

frequency RC

2π

frequency RC

2π

SLOPE OUTD mV

=−

⎛

⎝

⎜⎞

⎠

⎟+

⎛

⎝

⎜⎞

⎠

⎟

25 320

SLOPE OUTA OR OUTB mV

RorR k

=⎛

⎝

⎜⎞

⎠

⎟

()

⎡

⎣

⎢

⎤

⎦

⎥

91240

MAX2016

LOGARITHMIC

DETECTOR

TRANSMITTER

SET-POINT

DAC

OUTA/

OUTB

SETA/

SETB

COUPLER

RFINA/

RFINB

POWER AMPLIFIER

GAIN-CONTROL INPUT

LOWPASS

FILTER

20kΩ

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 con-

troller/detector, the second channel can be easily implemented

by using the adjacent set of input and output connections.)

MAX2016

LF-to-2.5GHz Dual Logarithmic Detector/

Controller for Power, Gain, and VSWR Measurements

16 ______________________________________________________________________________________

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 compara-

tors 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 condi-

tions. These comparators are high-speed devices.

Connect high-value bypass capacitors (0.1µF) 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 hystere-

sis 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 hystere-

sis. Set the parallel combination of resistors connected

to CSETL to be less than 10kΩfor best performance.

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 sup-

ply 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 37.4Ω(±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

MAX2016

RFINA

RFINB

LOGARITHMIC

DETECTOR

LOGARITHMIC

DETECTOR OUTD

SETD

COUPLER COUPLER

RF BLOCK

OUT

CSETL

COR

CSETH

20kΩ

Figure 8. Window Comparators Monitoring Mode. COR goes high if OUTD drops below CSETL or rises above CSETH.

MAX2016

LF-to-2.5GHz Dual Logarithmic Detector/

Controller for Power, Gain, and VSWR Measurements

______________________________________________________________________________________ 17

MAX2016

REFSETA OUTA OUTB SETB

2.0V

REF

LOG

AMPLIFIERS

LOG

AMPLIFIERS

VCC

RFINB+

RFINB-

FB1

FB2

FV1

FV2

SETDOUTDCSETH COUTH COUTL CSETL

COR

FA2

FA1

RFINA-

RFINA+

GND

EXPOSED

PAD

20kΩ

50Ω50Ω

20kΩ20kΩ20kΩ

2, 9, 12, 20

5, 17

16 15 11 10

2423252726

20kΩ

Functional Diagram

planes. This method provides a good RF/thermal con-

duction 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.

Power-Supply Bypassing

Proper voltage-supply bypassing is essential for high-

frequency circuit stability. Bypass each VCC pin with a

capacitor as close to the pin as possible (Typical

Application Circuit).

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 low-

RF 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).

MAX2016

LF-to-2.5GHz Dual Logarithmic Detector/

Controller for Power, Gain, and VSWR Measurements

18 ______________________________________________________________________________________

FA1

VCC

RFINA+

RFINA-

GND

COUTH

CSETH

FB1 21

VCC

RFINB+ 19

RFINB- 18

GND 17

COUTL 16

CSETL 15

COR

VCC

SETD

OUTD

VCC

FV2

FV1

FA2

OUTA

SETA

REF

SETB

OUTB

FB2

MAX2016

VREF

VOUTA

VOUTB

C12C5

C11

C16 C17

COMPARATORB

C15

A + B

C7 C14

VOUTD

VCC

VCC VCC

VCC

C18

COMPARATORA

RFINA RFINB

C10

C13

EXPOSED

PADDLE

NOTE: COMPARATORS ARE DISABLED

BY CONNECTING CSETL AND CSETH TO VCC.

Typical Application Circuit

Chip Information

PROCESS: BiCMOS

DESIGNATION VALUE DESCRIPTION

C1, C2, C8, C9 680pF Microwave capacitors (0402)

C3, C6, C10, C13 33pF Microwave capacitors (0402)

C4, C7, C11, C14 0.1µF Microwave capacitors (0603)

C5, C12, C15, C16, C17 Not used Capacitors are optional for frequency compensation, bypass

C18 10µF Tantalum capacitor (C case)

R1, R2, R3 0ΩResistors (0402)

0ΩResistor (1206) for VS = 2.7V to 3.6V

R6 37.4Ω±1% resistor (1206) for VS = 4.75V to 5.25V

Table 1. Component Values Used in the Typical Application Circuit

MAX2016

LF-to-2.5GHz Dual Logarithmic Detector/

Controller for Power, Gain, and VSWR Measurements

______________________________________________________________________________________ 19

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.)

QFN THIN.EPS

MAX2016

LF-to-2.5GHz Dual Logarithmic Detector/

Controller for Power, Gain, and VSWR Measurements

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

MAX2016MAX2016

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