Patent ID: 7076008

Claim:
A circuit, comprising: a direct conversion receiver coupled to receive a radio frequency signal and produce an analog signal; an analog to digital converter coupled to receive the analog signal and produce baseband digital input signals having real and imaginary components; and a digital baseband circuit, comprising: first and second input ports for receiving the digital input signals; and a controller coupled to the first and second input ports for estimating the gain and phase imbalance of the digital input signals, wherein the controller estimates the gain mismatch as; - Î³ ^ = g I g Q = Î± I - Î² Q Î± I + Î² Q , where g I , g Q are the gains of the real and imaginary components of the digital input signals, Î± I is a pilot symbol despread by a normal spreading sequence and Î² Q is the pilot symbol despread by an IQ-swapped spreading sequence.