一、引言砷化镓肖特基势垒场效应晶体管是在X波段和更高频率上显示线性功率放大性能的第一个三端固体器件。它的独特的信号处理能力和低噪声特性已为许多工作者所证明。例如,在10千兆赫时,其噪声系数接近3分贝的已有报导,而理论上预计的还低一些。目前,从低的C波段往上,砷化镓场效应晶体管已在低噪声放大器中被采用。就这点而论,它很出色地弥补了硅双极晶体管仍然只能控制C波段以下的微波波段的状况,然而,现在正用具有缓冲层的场效应晶体管来实现降低噪声,双极晶体管的这一独特频率范围不会继续存在多久。图1是根据1975年7月用硅双极晶体管和砷化镓场效应晶体管 I. INTRODUCTION Gallium arsenide Schottky barrier FETs are the first three-terminal solid state devices that exhibit linear power amplification performance in the X-band and at higher frequencies. Its unique signal processing capability and low noise characteristics have proven itself by many workers. For example, at 10 gigahertz it has been reported that its noise figure approaches 3 dB, which is theoretically expected to be lower. Currently, gallium arsenide field effect transistors have been used in low noise amplifiers from the low C band. In this regard, it is very good to make up for the silicon bipolar transistor still can only control the C-band microwave band below the condition, however, is now using a buffer layer FET to achieve noise reduction, bipolar transistor This unique frequency range will not last long. Figure 1 is based on July 1975 with silicon bipolar transistors and gallium arsenide field effect transistors