A Wide Gain Range Variable Gain Amplifier with Exponential Gain Control

A wide gain range CMOS variable gain amplifier with exponential gain control is designed using SMIC 0.35μm CMOS mix-signal process.The amplifier has been used in one IRDA IC.The variable gain amplifier consists of Gilbert cell, exponential generator and a stage of a fixed-gain amplifier.After simulation with HSPICE,this amplifier can achieve a continuous-gain control range of-11.3dB～33.4dB,5.2MHz bandwidth(-3dB),60°phase margin and control current make the gain vary linear-in-dB.It has well caught the performance index of whole IRDA IC.