Time-domain distortion of a pulse-operated high-power GaN amplifier and a reduction method

Abstract

This paper describes pulse waveform distortion by a high-power GaN amplifier and a method for reducing it in a solid-state radar that performs pulse compression. When a pulse signal is input to the amplifier, the output pulse waveform differs from the input form because of the influences of nonlinearity and transient response, which are remarkable at the time of rise and fall when the amplitude has a temporal slope. In the measurement results, the temporal slope and the pulse width increased by 79.6% and 1.5%, respectively, compared with the input waveform. On processing the received signal, these influences degraded the signal-to-noise ratio after pulse compression by about 5 dB. In the proposed method, these influences were reduced by adding a dummy signal before and after the desired signal. This method is advantageous in that it does not require the addition of a feedback circuit for distortion compensation and it is not easily influenced by changes in the signal settings and the ambient temperature.