Variable gain amplifier for dual mode WCDMA/GSM receivers

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 0.8mm²It 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 3V supply. The noise figure at maximum gain is 8.7dB. The IIP3 is -4dBm at minimum gain, while the OIP3 is - 1 dBm at maximum gain. The group delay for 5MHz bandwidth is 1.5ns. The performance of this VGA makes it usable for multimode applications.