Novel analysis of the cancellation performance of a feedforward amplifier

The IMD (inter-modulation distortion) cancellation performance of a feedforward amplifier is determined by amplitude imbalance, phase imbalance and delay mismatch between two paths in a linearization loop. The effects of these parameters on the cancellation performance are analyzed. In this paper, we show that the linearization bandwidth and the IMD cancellation performance of a linearization loop depend more on the delay mismatch than on the other parameters. Additionally, the total effective IMD cancellation performance of a feedforward amplifier is investigated. The effects of the first linearization loop on the effective IMD cancellation performance are compared to those of the second linearization loop and then the influences of an error amplifier on the effective IMD cancellation performance are analyzed.