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