Abstract:

Lots of designs of ALC are complex and costly.In this paper,a simple and low cost ALC is presented,which is composed of detection circuit,voltage controlled attenuator circuit and differential control circuit;and then the principles and circuit design of each part of the circuit is described in detail.ultimately the ALC loop achieve the output power flatness of 0.15 dB in more than 10% bandwidth of S-band,and output power variation is only 0.2 dB under the input signal 5±5 dBm.

Key words: power amplifier;ALC;voltage controlled attenuator;temperature compensation