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AD8307:  DC to 500 MHz, 92 dB Logarithmic Amplifier

Product Details


The AD8307 is the first logarithmic amplifier made available in an 8-lead (SOIC_N) package. It is a complete 500 MHz monolithic demodulating logarithmic amplifier based on the progressive compression (successive detection) technique, providing a dynamic range of 92 dB to ±3 dB law-conformance and 88 dB to a tight ±1 dB error bound at all frequencies up to 100 MHz. It is extremely stable and easy to use, requiring no significant external components. A single-supply voltage of 2.7 V to 5.5 V at 7.5 mA is needed, corresponding to an unprecedented power consumption of only 22.5 mW at 3 V. A fast acting CMOS-compatible control pin can disable the AD8307 to a standby current of less than 150 µA.

Each of the cascaded amplifier/limiter cells has a small signal gain of 14.3 dB, with a -3 dB bandwidth of 900 MHz. The input is fully differential and at a moderately high impedance (1.1 kΩ in parallel with about 1.4 pF). The AD8307 provides a basic dynamic range extending from approximately -75 dBm (where dBm refers to a 50 Ω source, that is, a sine amplitude of about ±56 µV) up to +17 dBm (a sine amplitude of ±2.2 V). A simple input matching network can lower this range to -88 dBm to +3 dBm. The logarithmic linearity is typically within ±0.3 dB up to 100 MHz over the central portion of this range, and degrades only slightly at 500 MHz. There is no minimum frequency limit. The AD8307 can be used at audio frequencies of 20 Hz or lower.

The output is a voltage scaled 25 mV/dB, generated by a current of nominally 2 μA/dB through an internal 12.5 kΩ resistor. This voltage varies from 0.25 V at an input of −74 dBm (that is, the ac intercept is at −84 dBm, a 20 μV rms sine input), up to 2.5 V for an input of +16 dBm. This slope and intercept can be trimmed using external adjustments. Using a 2.7 V supply, the output scaling can be lowered, for example to 15 mV/dB, to permit utilization of the full dynamic range.

The AD8307 exhibits excellent supply insensitivity and temperature stability of the scaling parameters. The unique combination of low cost, small size, low power consumption, high accuracy and stability, very high dynamic range, and a frequency range encompassing audio through IF to UHF makes this product useful in numerous applications requiring the reduction of a signal to its decibel equivalent.

The AD8307 operates over the industrial temperature range of -40°C to +85°C, and is available in 8-lead SOIC and PDIP packages.

Data Sheet, Rev D, 07/2008

FEATURES and BENEFITS

  • Complete multistage logarithmic amplifier
  • 92 dB dynamic range: –75 dBm to +17 dBm
    to –90 dBm using matching network
  • Single supply of 2.7 V minimum at 7.5 mA typical
  • DC to 500 MHz operation, ±1 dB linearity
  • Slope of 25 mV/dB, intercept of –84 dBm
  • Highly stable scaling over temperature
  • Fully differential dc-coupled signal path
  • 100 ns power-up time, 150 µA sleep current

Functional Block Diagram for AD8307

Documentation

Title Content Type File Type
AD8307: Low Cost DC-500 MHz, 92 dB Logarithmic Amplifier Data Sheet  (Rev D, 07/2008) (pdf, 501 kB) Data Sheets PDF
AN-1040: RF Power Calibration Improves Performance of Wireless Transmitters  (pdf, 152 kB) Application Notes PDF
AN-691: Operation of RF Detector Products at Low Frequency  (pdf, 778 kB) Application Notes PDF
Design and Operation of Automatic Gain Control Loops for Receivers in Modern Communication Systems  (pdf, 129 kB) Tutorials PDF
Detecting Fast RF Bursts Using Log Amps
(Analog Dialogue, Vol. 36, No. 5, September-October, 2002)
Analog Dialogue HTML
Ask The Applications Engineer - 28
Logarithmic Amplifiers-Explained

(Analog Dialogue, Vol. 33, No. 3, March, 1999)
Analog Dialogue HTML
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
RF Source Booklet  (PDF, 4353 kB)
RF IC Product Overview - Version P (02/2014)
Overview PDF
Industrial Applications Overview HTML
We measure portable performance in µA and MHz. In handheld designs, analog is everywhere. Overview HTML
ICs for Enhanced Handset User Experience Overview HTML
What is an RF Detector, and how is it used? FAQs/RAQs HTML
RAQs index Rarely Asked Questions HTML
Glossary of EE Terms Glossary HTML

Design Tools,Models,Drivers & Software

Title Content Type File Type
ADIsimRF
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 3.43
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

AD8307 Model Options
Model Package Pins Temp.
Range
Packing,
Qty
Price*(100-499) Price*1000 pcs RoHS View PCN/ PDN Check Inventory/
Purchase/Sample
AD8307ANZ Status: Production 8 ld PDIP 8 Ind Tube, 50 $7.19 $6.07 Y  Material Info PCN Purchase Sample
AD8307AR Status: Production 8 ld SOIC 8 Ind Tube, 98 $8.30 $7.01 N  Material Info Notify Me Purchase
AD8307AR-REEL Status: Production 8 ld SOIC 8 Ind Reel, 2500 - $7.01 N  Material Info Notify Me Purchase
AD8307AR-REEL7 Status: Production 8 ld SOIC 8 Ind Reel, 750 $8.30 $7.01 N  Material Info Notify Me Purchase
AD8307ARZ Status: Production 8 ld SOIC 8 Ind Tube, 98 $7.19 $6.07 Y  Material Info Notify Me Purchase Sample
AD8307ARZ-REEL Status: Production 8 ld SOIC 8 Ind Reel, 2500 - $6.07 Y  Material Info Notify Me Purchase
AD8307ARZ-RL7 Status: Production 8 ld SOIC 8 Ind Reel, 750 $7.19 $6.07 Y  Material Info Notify Me 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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