Research on Operational Amplifier Optimization Methods

This paper reviews three operational amplifier (opamp) topologies and their advances. An active-feedback frequency-compensation (AFFC) amplifier composed of three blocks provides higher low-frequency gain and bandwidth simultaneously for low power application. Better slew rate and smaller chip size are also achieved by this circuit. Except modification of compensation topology, recycling folded cascode (RFC) amplifier split the transistors to address the inefficient structure and enhanced bandwidth, slew rate and gain are obtained. Feedforward-Miller-compensation with pole-zero cancellation (FFMC-PZ) amplifier made further improvement on compensation topology and extend the unity-gain bandwidth to gigahertz. Detailed structure and analysis of three amplifiers will be discussed in this paper.