AD8317 Amplifier

GENERAL DESCRIPTION

The AD8317 is a demodulating logarithmic amplifier, capable of accurately converting an RF input signal to a corresponding decibel-scaled output. It employs the progressive compression technique over a cascaded amplifier chain, each stage of which is equipped with a detector cell. The device can be used in either measurement or controller modes. The AD8317 maintains accurate log conformance for signals of 1 MHz to 8 GHz and provides useful operation to 10 GHz. The input dynamic range is typically 55 dB (re: 50 Ω) with less than ±3 dB error. The AD8317 has 6 ns/10 ns response time (fall time/rise time) that enables RF burst detection to a pulse rate of beyond 50 MHz. The device provides unprecedented logarithmic intercept stability vs. ambient temperature conditions. A supply of 3.0 V to 5.5 V is required to power the device. Current consumption is typically 22 mA, and it decreases to 200 μA when the device is disabled.
The AD8317 can be configured to provide a control voltage to a power amplifier or a measurement output from the VOUT pin. Because the output can be used for controller applications, special attention has been paid to minimize wideband noise. In this mode, the setpoint control voltage is applied to the VSET pin.

FEATURES

Wide bandwidth: 1 MHz to 10 GHz
High accuracy: ±1.0 dB over temperature
55 dB dynamic range up to 8 GHz ± 3 dB error
Stability over temperature: ±0.5 dB
Low noise measurement/controller output, VOUT
Pulse response time: 6 ns/10 ns (fall/rise)
Small footprint, 2 mm × 3 mm LFCSP
Supply operation: 3.0 V to 5.5 V @ 22 mA
Fabricated using high speed SiGe process

APPLICATIONS

RF transmitter PA setpoint control and level monitoring
Power monitoring in radio link transmitters
RSSI measurement in base stations, WLANs, WiMAX, and radars