Variable Gain Amplifier for Dual Mode WCDMA/GSM Receivers

摘要

A Variable Gain Amplifier (VGA) is designed for a WCDMA/GSM subsampling receiver. The VGA is implemented in a 0.35μm CMOS process and approximately occupies 0.8mm~2. It operates at an IF frequency of 246MHz. The VGA provides a 60dB digitally controlled gain range in 2dB steps. The overall gain accuracy is less than 0.3dB. The current is 9mA at 3 V supply. The noise figure at maximum gain is 8.7dB. The IIP3 is -4dBm at minimum gain, while the OIP3 is -1dBm at maximum gain. The group delay for 5MHz bandwidth is 1.5ns. The performance of this VGA makes it usable for multimode applications.