A quadrature data-dependent DEM algorithm to improve image rejection of a complex /spl Sigma//spl Delta/ modulator

A data-dependent DEM algorithm is controlled by the quadrature bitstreams of a complex /spl Sigma//spl Delta/ modulator. The quadrature feedback paths of the modulator are dynamically matched, without increasing the in-band noise. Test chips with an initial 20% mismatch have a typical image rejection ratio of 61 dB with DEM.