갈륨비소 MESFET를 이용한 고이득 연산 증폭기의 입력단 설계

Abstract

In the high speed analog system, satellite communication system, video signal processiong and optical fiber interface circuits,GaAs high gain operational amplifier is advantageous due to its high electron mobility, peak electron velocity and semi-insulating substance. But it is difficult to obtain a high gain because of its low transconductance and other drawbacks, such as low frequency dispersion and process variation. Therefore in this paper, a circuit techniques for improving the voltage gain of the GaAs MESFET amplifier is presented. Also, various types of existing current mirror and current mirror proposed are compared. To obtain the high differential gain, bootstrap gain enhancedment technique is used and common mode feedback is employed in differential amplifier. The simulation results show that gain is higher than that of basic amplifier about 18.6dB, and stability and frequency performance of fdifferential amplifier are much improved.