Patent attributes
A direct conversion wireless transmitter includes IQ mismatch pre-compensation using direct learning adaptation to adjust IQ pre-compensation filtering. Widely-linear IQ_mismatch pre-compensation filtering compensates for IQ mismatch in the TX analog chain, filtering of input data x(n) to provide pre-compensated data y(n) with a compensation image designed to interfere destructively with the IQ_mismatch image. A feedback receiver FBRX captures feedback data z(n) used for direct learning adaptation. DL adaptation adjusts IQ_mismatch filters, modeled as an x(n)_direct and complex conjugate x(n)_image transfer functions w1 and w2, including generating an adaptation error signal based on a difference between TX/FBRX-path delayed versions of x(n) and z(n), and can include estimation and compensation for TX/FBRX phase errors. DL adaptation adjusts the IQ pre-comp filters w1/w2 to minimize the adaptation error signal. Similar modeling can be used for IQ mismatch. The IQ_mismatch pre-compensator can be implemented as a combination of digital signal processing and hardware acceleration.
