Comparative Study of CMOS Input & Output Amplifier

Abstract

It is inconceivable to implement any analog circuit without the use of amplifiers in one form or another. The amplifiers are the essential part of the analog designs. Amplifiers consists of input amplifiers to primarily provide the gain and output amplifiers are used to provide sufficient power to the output load and to drive a speaker or other power device. Another important purpose of output stage is the input-output matching of devices with which it is cascaded. An output stage plays a crucial role in the circuit design. The output stage with minimum distortion, low output impedance, high bandwidth, and high efficiency is desired. In this project, some amplifiers to be used as output amplifiers are designed to drive the RC load with RL=2K and CL=10 pF. Here, I have studied performance parameters like Total Harmonic Distortion, efficiency, Bandwidth, output voltage swing, dc gain, output resistance, temperature effects for class A current source load class A sinking amplifiers(without and with feedback), push-pull class B and AB output amplifiers (without and with feedback) and cascode amplifiers. The results for the same are tabulated in the concluding chapter, which would facilitate the design engineer to make a choice between the various modalities for a specific application. Source degeneration technique to reduce the total harmonic distortion and error amplifier to reduce the output resistance are also presented in this project. 4 Differential amplifiers are also studied and two topologies i.e. resistive load differential amplifier, and current mirror load differential amplifier is designed to be used as input amplifiers. The layouts of class A common source sinking amplifier, class B push-pull amplifier without feedback and differential amplifier is also presented.