Low power high speed amplifier design

Abstract

The operational amplifier (op-amp) is one of the important component in analog to digital converters. The power consumption of these converters mostly depend on the op-amps used. The accuracy and speed performance of analog to digital converters can also be affected due to the finite DC gain and finite bandwidth of the opamp. So the design of op-amp is very critical for these applications.

This thesis describes the design of a telescopic operational amplifier. Of the several architectures, a telescopic operational amplifier provides better frequency response and also consumes least power in comparison with other topologies. The limited swing of the telescopic amplifier has been improved by using the current source load transistors in the linear region. Two gain boosting amplifiers are also used to enhance the gain of the amplifier. This gain boosting amplifiers uses a folded - cascode topology. The overall circuit is designed in 0.18 micron CMOS technology at a supply voltage of 1.8 Volt.

The operational amplifier achieves a dc gain of 72 dB, bandwidth of 390 MHZ, slew rate of 132 V/ µs and a differential output swing of ± 0.82 V. The overall circuit consumes a total power of 3.36 mw.