Patent ID: 7567783

Claim:
A method of calibrating an I/Q mismatch of a direct conversion receiver comprising: receiving a packet comprising a known waveform having a two-dimensional I versus Q trajectory via a direct conversion receiver, wherein an I/Q mismatch of the direct conversion receiver distorts the known waveform such that the direct conversion receiver provides a distorted packet including an observed distorted waveform; determining a distortion matrix defining the distortion of the known waveform due to the I/Q mismatch of the direct conversion receiver based on the known waveform and the observed distorted waveform by: correcting the known waveform with a first trial frequency offset to provide a frequency-corrected known waveform; time aligning the frequency-corrected known waveform with the observed distorted waveform; computing a first distortion matrix based on a least squares fit of a distorted version of the frequency-corrected time aligned known waveform to the observed distorted waveform with respect to components of the distortion matrix applied to the frequency-corrected time aligned known waveform; determining a residual error based on the first trial frequency offset and the first distortion matrix; repeating the correcting, time aligning, computing, and determining the residual error steps for at least one additional trial frequency offset, thereby computing at least one additional distortion matrix; and selecting the distortion matrix and a desired frequency offset from the first and at least one additional trial frequency offsets and distortion matrices by selecting one of the first and at least one additional trial frequency offsets and distortion matrices having a minimum residual error; and compensating subsequent packets received by the direct conversion receiver based on the distortion matrix, thereby compensating for the I/Q mismatch of the direct conversion receiver.