A linearized amplifier using self-mixing feedback technique

Abstract

A linearized amplifier using self-mixing feedback technique is presented to cancel out third-order intermodulation distortion (IMD3) terms. Second harmonic terms, which are generated by the self-mixing mixer between base and collector of a BJT amplifier, can be used as a source for IMD3 cancellation. The amplifier is based on a common emitter BJT amplifier with a passive FET mixer and an emitter follower for self-mixing feedback. The amplifier has been implemented with discrete transistors on an FR-4 PCB. Up to 16-dB IMD3 rejection has been achieved by the self-mixing feedback technique at 2 GHz with peak output power of 20 dBm.