一种应用于AGC的可编程CMOS指数函数发生器  

A Programmable Generator of CMOS Exponential Function for AGC Applications

作　　者：吴明权[1] 李志军[1] 

机构地区：[1]湘潭大学信息工程学院,湖南湘潭411105

出　　处：《微电子学与计算机》2015年第6期90-95,100,共7页Microelectronics & Computer

基　　金：国家自然科学基金项目(61176032)

摘　　要：在无线接收机中,要达到在不同的信号功率下,AGC环路都具有相同的瞬态响应和确切的环路建立时间,VGA的增益需要按照指数规律变化.因此基于差分跨导电路、平方电路及乘法器提出了一种应用于AGC的可编程CMOS指数函数发生器.该函数发生器采用了四阶泰勒近似方法,通过控制外部偏置电压可以精确逼近不同指数函数.采用TSMC 0.5μm CMOS集成工艺对电路进行PSPICE仿真测试,结果表明,输入范围-1.54≤x≤3.15,输出动态范围达到40dB,误差在±0.5dB之内,且可以实现不同指数函数的编程,非常适合应用于高性能AGC系统的实现.In the wireless receiver,in order to ensure that AGC loop has the same transient response and the exact settling time,when signal power are different,the VGA gain is realized according to the exponential changes.Therefore,aprogrammable CMOS exponential function generator for AGC applications are presented,which is based on the differential transconductor circuit,square circuit and multiplier.The method of the fourth-order Taylor approximation is adopted in the function generator,and the different exponent function can be approximated accurately by the controlled external offset voltage.The proposed circuit is simulated and analyzed by PSPICE with TSMC 0.5μm CMOS technology parameters,the results show that a nearly 40 dB output dynamic range is obtained with the error less than ±0.5dB over an input range-1.54≤x≤3.15,and the different exponent function can be implemented and programmed,which are very suitable for application to the high performance AGC system implementation.

关 键 词：四阶泰勒近似 不同指数 编程 函数发生器 指数函数 

分 类 号：TN432[电子电信—微电子学与固体电子学]