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Product Details

The AD606 is a complete, monolithic logarithmic amplifier using a 9-stage "successive-detection" technique. It provides both logarithmic and limited outputs. The logarithmic output is from a three-pole post-demodulation low-pass filter and provides a loadable output voltage of +0.1 V dc to +4 V dc. The logarithmic scaling is such that the output is +0.5 V for a sinusoidal input of -75 dBm and +3.5 V at an input of +5 dBm; over this range the logarithmic linearity is typically within ±0.4 dB. All scaling parameters are proportional to the supply voltage.

The AD606 can operate above and below these limits, with reduced linearity, to provide as much as 90 dB of conversion range. A second low-pass filter automatically nulls the input offset of the first stage down to the submicrovolt level. Adding external capacitors to both filters allows operation at input frequencies as low as a few hertz.

The AD606's limiter output provides a hard-limited signal output as a differential current of ±1.2 mA from open-collector outputs. In a typical application, both of these outputs are loaded by 200 Ω resistors to provide a voltage gain of more than 90 dB from the input. Transition times are 1.5 ns, and the phase is stable to within ±3° at 10.7 MHz for signals from -75 dBm to +5 dBm.

The logarithmic amplifier operates from a single +5 V supply and typically consumes 65 mW. It is enabled by a CMOS logic level voltage input, with a response time of <5 µs. When disabled, the standby power is reduced to <1 mW within 5 µs.

The AD606J is specified for the commercial temperature range of 0°C to +70°C and is available in 16-pin plastic DIPs or SOICs. Consult the factory for other packages and temperature ranges.

An evaluation board is available for this product and may be ordered using the following product number: AD606-EB.


  • Logarithmic amplifier performance
    -75 dBm to +5 dBm dynamic range
    <1.5 nV/√Hz input noise
    Usable to >50 MHz
    37.5 mV/dB voltage output
    On-chip low-pass output filter
  • Limiter performance
    ±1 dB output flatness over 80 dB range
    ±3° phase stability at 10.7 MHz over
    80 dB range
    Adjustable output amplitude
  • Low power
    +5 V single supply operation
    65 mW typical power consumption
    CMOS-compatible power-down to
    325 µW typ
    <5 µs enable/disable time

Functional Block Diagram for AD606


Title Content Type File Type
AD606: 50 MHz, 80 dB Demodulating Logarithmic Amplifier with Limiter Output Data Sheet  (Rev B, 08/1999) (pdf, 448 kB) Data Sheets PDF
AN-202: An IC Amplifier User’s Guide to Decoupling, Grounding, and Making Things Go Right for a Change  (pdf, 76 kB) Application Notes PDF
AN-405: 05: Increasing the Speed of the Output Response of the AD606  (pdf, 156 kB) Application Notes PDF
Measurement and Control of RF Power
by Eamon Nash, Analog Devices, Inc.
Technical Articles HTML
Detecting Fast RF Bursts using Log Amps  (pdf, 174 kB)
by Yuping Toh, Analog Devices, Inc.
Technical Articles PDF
Make Precise Base-Station Power Measurements  (pdf, 1764 kB)
(Microwaves and RF, November 2002)
Technical Articles PDF
Log Amps and Directional Couplers Enable VSWR Detection  (pdf, 2223 kB)
by Anil Rachakonda and Larry Hawkins, Analog Devices, Inc. (RF Design, 1/1/2007)
Technical Articles PDF
Measuring VSWR and Gain in Wireless Systems  (pdf)
By Eamon Nash, Analog Devices Inc., (Microwave Journal, Nov 2005)
Technical Articles PDF
Measuring the RF Power in CDMA2000 and W-CDMA High Power Amplifiers (HPAs)  (pdf, 609 kB)
By Larry Hawkins, Analog Devices, Inc. (MPD Digest, Nov. 2005)
Technical Articles PDF
Design a Logamp RF Pulse Detector  (pdf, 338 kB)
by Eamon Nash
(Microwaves & RF, January 1, 2000)
Technical Articles PDF
Detecting Fast RF Bursts Using Log Amps
(Analog Dialogue, Vol. 36, No. 5, September-October, 2002)
Analog Dialogue HTML
Choosing High-Speed Signal Processing Components for Ultrasound Systems
(Analog Dialogue, Vol. 29, No. 2, 1995)
Analog Dialogue HTML
Ask The Applications Engineer - 28
Logarithmic Amplifiers-Explained

(Analog Dialogue, Vol. 33, No. 3, March, 1999)
Analog Dialogue HTML
Industrial Applications Overview HTML
RAQs index Rarely Asked Questions HTML
What is an RF Detector, and how is it used? FAQs/RAQs HTML
Glossary of EE Terms Glossary HTML

Design Tools,Models,Drivers & Software

Title Content Type File Type
ADI’s ADIsimRF design tool provides calculations for the most important parameters within the RF signal chain, including cascaded gain, noise figure, IP3, P1dB, and total power consumption.
ADIsim Design/Simulation Tools HTML
ADIsimPLL™- Version 3.60.10
ADIsimPLL enables the rapid and reliable evaluation of new high performance PLL products from ADI. It is the most comprehensive PLL Synthesizer design and simulation tool available today. Simulations performed include all key non-linear effects that are significant in affecting PLL performance. ADIsimPLL removes at least one iteration from the design process, thereby speeding the design- to-market.
ADIsim Design/Simulation Tools HTML

Evaluation Kits & Symbols & Footprints

Symbols and Footprints— Analog Devices offers Symbols & Footprints which are compatible with a large set of today’s CAD systems for broader and easier support.

SampleSample & Buy

Price, packaging, availability

AD606 Model Options
Model Package Pins Temp.
Price*(100-499) Price*1000 pcs RoHS View PCN/ PDN Check Inventory/
AD606JCHIPS Status: Production CHIPS OR DIE 0 Comm. Tray, 88 $27.51 $22.00 Y  Material Info Notify Me Purchase
AD606JN Status: Production 16 ld PDIP 16 Comm. Tube, 25 $36.91 $33.36 N  Material Info PCN Purchase
AD606JNZ Status: Production 16 ld PDIP 16 Comm. Tube, 25 $33.62 $30.38 Y  Material Info PCN Purchase
AD606JR Status: Production 16 ld SOIC 16 Comm. Tube, 48 $36.91 $33.36 N  Material Info PCN Purchase
AD606JR-REEL7 Status: Production 16 ld SOIC 16 Comm. Reel, 1000 - $33.36 N  Material Info PCN Purchase
AD606JRZ Status: Production 16 ld SOIC 16 Comm. Tube, 48 $33.62 $30.38 Y  Material Info PCN Purchase
AD606JRZ-REEL7 Status: Production 16 ld SOIC 16 Comm. Reel, 1000 - $30.38 Y  Material Info PCN Purchase
Price Table Help

The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.

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