Efficiency Enhancement Technique for Feed-Forward Amplifier Using Negative Group Delay Circuit

We present a design and an implementation of a multistage negative group delay circuit. It is small in size and has a compact circuit. Each stage of the multistage circuit is composed of three lumped resonators with resisters. To obtain the good reflection, the resonators are arranged in the π circuit. We discuss the principle of the negative group delay circuit and apply the circuit to the feed-forward amplifier. The delay line of the distortion cancellation loop is shortened 40% by connecting the circuit to the driver stage of the error amplifier. The efficiency of the feed-forward amplifier has been improved from 9% to 12%.