Active protection circuit for load mismatched power amplifier

摘要

A peak detector detects an amplifier output overvoltage condition if the amplifier drives a mismatched load impedance. In response to the detected overvoltage condition, a clamping transistor lowers a reference DC bias voltage supplied by a bias circuit to the amplifier. The lowered reference DC bias voltage lowers amplifier gain and output power, thus protecting the amplifier.