题目/Title：一种低电压、低噪声、低失真的语音信号自动增益控制电路
                        A low noise low distortion Automatic Gain Control circuit

作者/Author：王明轩,李冬梅
                        Mingxuan Wang,Dongmei Li

期刊/Journal：微电子学与计算机 Microelectronics & Computer

年份/Issue Date：2016.Nov.

卷（期）及页码/Volume（No.）&pages：Vol.33, No.11, pp. 114 - 118

摘要/Abstract：
本文提出了一种工作在低电压下的宽动态范围、低噪声、低失真度的可用于语音信号采集系统的自动增益控制电路（AGC）。该AGC环路采用反馈式结构，数字式增益控制。设计指标为1V工作电压；0-40dB增益动态范围，2dB增益步长；8kHz带宽。采用π型电阻网络作为环路中可变增益放大器的无源反馈网络，提高增益的准确性并实现增益在对数单位下的线性。采用滞回比较器来减弱当峰值检测器输出信号在阈值电压附近小幅度快速变化而引起的抖动。基于0.18μm CMOS工艺完成电路及版图设计，芯片面积约为0.45mm2。提取版图寄生
This paper presents a kind of Automatic Gain Control (AGC) circuits which can be used in speech signal acquisition system, it has high gain range, low noise and high linearity. The proposed AGC is based on feedback topologies and the gain is digital controlled. The design indexes are: 1V supply voltage, 0~40dB gain range, 2dB gain step, 8 KHz bandwidth. A π-type resistors network is used in the Programmable Gain Amplifier (PGA) as the passive feedback device to realize gain linearity in decibels and increase the gain accuracy. The hysteresis comparator eliminate the chattering effects when the output signal of Peak Detector changes rapidly around the threshold. The design is implemented in 0.18μm CMOS and occupies an active area of 0.41mm2. The power consumption of AGC is about 0.17mW at 1V supply voltage. The gain of AGC loop ranges from 0dB to 40.2dB in 2dB step with gain error not more than 0.2dB. The total harmonic distortion (THD) is below -70dB over the audio frequencies at 0.4-Vpp differential output. The integrated noise in the audio range (20 Hz~20 kHz) is less than 5μVRMS when the gain is set at 0dB.