GENERAL DESCRIPTION

The AD8313 is a complete multistage demodulating logarithmic amplifier that can accurately convert an RF signal at its input to an equivalent decibel-scaled value at its dc output. The AD8313 maintains a high degree of log conformance for signal frequencies from 0.1 GHz to 2.5 GHz. Application is straightforward, requiring only a single supply of 2.7 V to 5.5 V and the addition of a suitable input and supply decoupling. Operating on a 3 V supply, its 13.7 mA consumption (for TA = 25°C) is only 41 mW. A power-down feature is provided; the input is taken high to initiate a low current (20 µA) sleep mode, with a threshold at half the supply voltage.

The AD8313 is fabricated on Analog Devices, Inc., advanced 25 GHz silicon bipolar IC process and is available in an 8-lead MSOP package. The operating temperature range is −40°C to +85°C.

FEATURES

Wide bandwidth: 0.1 GHz to 2.5 GHz min

High dynamic range: 70 dB to ±3.0 dB

High accuracy: ±1.0 dB over 65 dB range (@ 1.9 GHz)

Fast response: 40 ns full-scale typical

Controller mode with error output

Scaling stable over supply and temperature

Wide supply range: 2.7 V to 5.5 V

Low power: 40 mW at 3 V

Power-down feature: 60 mW at 3 V

Complete and easy to use

APPLICATIONS

RF transmitter power amplifier setpoint control and level

monitoring

Logarithmic amplifier for RSSI measurement cellular base

stations, radio link, radar