Balanced Power Amplifier Protection Against Load Mismatch

This letter presents a new approach for balanced power amplifier protection against load mismatch under pulsed-RF operation. The proposed protection mechanism completely eliminates the reflected power under severe mismatch conditions while not affecting nominal operating condition. The concept is based on detection, comparison, and switching technique. The proposed protection circuit offers full protection against open and short at the output. This protection mechanism has been demonstrated on a 10-W X-band power amplifier, intended to be used in space borne radar payloads. The reaction time of the proposed protection mechanism is < 100 ns.