一种dB线性数字控制可变增益放大器的设计  

Design of a dB-Linear Digitally-Controlled Variable Gain Amplifier

作　　者：杨骁[1,2] 齐骋[1,2] 黄炜炜[1,2] 凌朝东 

机构地区：[1]华侨大学信息科学与工程学院,福建厦门361021 [2]厦门市专用集成电路与系统重点实验室,福建厦门361008

出　　处：《微电子学》2012年第1期9-12,共4页Microelectronics

基　　金：福建省自然科学基金资助项目(2010J05135);厦门市科技计划项目(3502Z0113015)

摘　　要：设计了一种dB线性增益的数字控制可变增益放大器。以二极管做负载的全差分输入共源极放大器为原型,通过同时同比例地改变输入输出晶体管尺寸比和偏置电流比来控制增益变化,使输入输出晶体管的电流密度保持一恒定值,提高了电路在低增益时的线性度。电路采用NEC 0.35μm CMOS标准工艺库进行设计。仿真结果表明,dB线性增益范围为-11.85dB到11.64dB,增益误差小于0.5dB。增益为-11.85dB时,其1-dB压缩点达到8.35dBm,-3dB增益带宽大于62MHz,并且随设定的增益值在62MHz和240MHz之间变化。A decibel-linear digitally-controlled variable gain amplifier（VGA） was designed based on common-source amplifier with diode-connected load.The gain of the amplifier was controlled by simultaneously changing bias current ratio and transistor size ratio,which made current density of input/diode-connected transistors stay constant with gain variation and achieved significant improvement in linearity at low gains.The circuit was designed in NEC 0.35-μm CMOS process.Simulation results showed that the circuit had a dB-linear gain ranging from-11.85 dB to 11.64 dB with gain error less than 0.5 dB,a 1-dB compression point of 8.35 dBm for gain setting of-11.85 dB,and a-3 dB bandwidth above 62 MHz,which may vary between 62 MHz and 240 MHz depending on gain setting.

关 键 词：dB线性增益 数字控制可变增益放大器 DC失调消除 

分 类 号：TN432[电子电信—微电子学与固体电子学]