GENERAL DESCRIPTION

The AD8318 is a demodulating logarithmic amplifier, capable of accurately converting an RF input signal to a corresponding decibel-scaled output voltage. It employs the progressive compression technique over a cascaded amplifier chain, each stage of which is equipped with a detector cell. The device is used in measurement or controller mode. The AD8318 maintains accurate log conformance for signals of 1 MHz to 6 GHz and provides useful operation to 8 GHz. The input range is typically 60 dB (referenced to 50 Ω) with error less than ±1 dB. The AD8318 has a 10 ns response time that enables RF burst detection to beyond 45 MHz. The device provides unprecedented logarithmic intercept stability vs. ambient temperature conditions. A 2 mV/°C slope temperature sensor output is also provided for additional system monitoring. A single supply of 5 V is required. Current consumption is typically 68 mA. Power consumption decreases to

FEATURES

Wide bandwidth: 1 MHz to 8 GHz

High accuracy: ±1.0 dB over 55 dB range (f < 5.8 GHz)

Stability over temperature: ±0.5 dB

Low noise measurement/controller output (VOUT)

Pulse response time: 10 ns/12 ns (fall/rise)

Integrated temperature sensor

Small footprint LFCSP

Power-down feature: <1.5 mW at 5 V

Single-supply operation: 5 V at 68 mA

Fabricated using high speed SiGe process

APPLICATIONS

RF transmitter PA setpoint control and level monitoring

RSSI measurement in base stations, WLAN, WiMAX, and

radars