APPLICATION OF DOHERTY AMPLIFIER AS PREDISTORTION CIRCUIT FOR LINEARIZING MICROWAVE AMPLIFIER

摘要

PROBLEM TO BE SOLVED: To provide a predistortion circuit for a microwave amplifier, particularly a predistortion circuit configured as a Doherty amplifier. SOLUTION: The predistortion circuit 40 is configured, to be coupled to a downstream Doherty amplifier 20 to precompensate for the gain compression and phase expansion of the amplifier 20 as the input power level is increased, while simultaneously reducing the intermodulation(IM) distortion. In order to execute precompensation, a precompensation circuit is operated at bias level, to obtain gain expansion and phase compression for canceling out the gain compression and phase expansion of the amplifier 20, to provide a higher overall linear power addition efficiency(PAE).