통신용 전력증폭기의 AM/AM 과 AM/PM을 독립적으로 제어하는 전치왜곡보상기 설계에 대한 연구

A Study of Predistorter for Independently Controllable AM/AM and AM/PM of Power Amplifier for the Communication System

Amplifier linearity plays a major role in the quality of mordem communication systems. The power amplifier should be operated near saturation region to achieve high efficiency. But at this region amplitude and phase distortions of the amplifier remarkably increase with the input power increase and cause a significant adjacent channel interference. In this paper, an independently controllable AM/AM and AM/PM predistortion linearizers consisted of two bias feed resistance linearizers is proposed. This linearizer allows independent adjustment of the AM/AM and AM/PM curves by using two adjustable voltages to compensate the power amplifier non-linearities. The predistortion linearizer can improve the ACPR by 5.3dB with cdma2000 multi carrier signals. And by applying this linearizer to two-tone(880MHz) power amplifier, third order IMD products are improved up to 8[dB].