Design of Low-Voltage High-Gain Current-Mode Operational Amplifier

Abstract

In this thesis a high-gain current-mode operational amplifier has been designed which is current-mode counterpart of traditional voltage-mode operational amplifier. It has been implemented using a transimpedance input stage followed by a transconductance output stage. Negative feedback around the high-gain current operational amplifier (COA) produces an accurate closed-loop current gain insensitive to process, supply and temperature variations. An analysis of the COA is presented along with possible applications. The design has been implemented on UMC 0.18 μm CMOS n-well process. The current operational amplifier exhibits an open-loop differential gain of 65.38 dB with the unity gain frequency of 353.60 MHz and a settling time of 5.90 ns. The applications of the COA include the implementation of instrumentation amplifier, current comparator with hysteresis, gyrator, and differential switched-current filter.