Help needed - Automatic Gain Control Circuit

[A_D_G]

Hi,

I need help on designing a AGC for WLAN 802.11g application. The current problem is that although the power is controlled well, the signal is kind of distorted and demodulated signal constellation degrades significantly. EVM was about 22% for -40dBm received WLAN signal.

Thank you very much.
A_D_G

 

[yorande]

by "power is controlled well" u mean the output power is constant, do u?
do u have external gain control?
I think there is linearity problem in ur circuit.
Have a try using much smaller input.