Precision Cmos Programmable Gain Amplifier Research And Design

In the area of wireless communication, disk reading, medical treatment and etc, Variable Gain Amplifier (VGA) is an key module in the electronic system. VGA, test circuit and error amplifier constitute the Automatic Gain Control (AGC) which offers constant signal power for subsequent circuit to prevent that system works irregularly by too weak signal or be saturated by large signal. It greatly improves the dynamic range of the system, and AGC helps the subsequent circuit to play better performance.This thesis firstly introduces the basic concept of AGC, and states the principle and design requirements of VGA. Then it studies some typical structures of VGA from analog gain control and digital gain control, and analyzes the advantages and drawbacks in each structure. At last, it studies some accurate gain control techniques that apply at high-accuracy VGA design.This thesis designs a wide-band programmable gain amplifier (PGA) with accurate gain step control. On the basis of traditional resistor network attenuator, it provides a new method of gain control. This method adopts two overlapping feedback loops, and realizes exact gain step control by changing trans-conductance ratio of the two loops. The circuit is manufactured by SMIC 0.13um RF CMOS process, and its area is 1.5mm×1mm. It's shown from the test result that the power consumption is 24mW under the supply voltage of 1.2V, the-3dB bandwidth is 600MHz. The gain accuracy could get 0.08dB in the gain range of 24dB, while the IIP3 are 18.8dBm and-5.57dBm under the gain of OdB and 24dB, respectively.