Design And Analysis Of Programmable Gain Amplifier

Programmable Gain Amplifier(PGA) is an important module in the integrated circuits. It is widely used in wireless communication system, medical treatment and etc. PGA is an important part of Automatic Gain Control(AGC) loop,AGC loop offers constant signal amplitude for subsequent circuit to prevent that integrated circuits work saturated by large input signal or be irregularly by too weak input signal and helps the subsequent circuit to play better system performance.This paper research from the basic concept of AGC loop, and introduce the principle and some design index of PGA. Then it studies some typical structures of PGA from open loop structures and closed loop structures. Meanwhile, it introduces several accurate gain control methods that apply at high precision PGA design.Based on the detailed theoretical analysis of PGA, a PGA has been designed. Very detailed analysis of gain boosting technique, wide-swing current mirror and common mode feedback circuit which involve in the design process. Design has been achieved in TSMC0.18um CMOS process, the simulation result shows the performance of the PGA meets the expected requirements.