A quadrature data-dependent DEM algorithm to improve image rejection of a complex ΣΔ modulator

L.J. Breems, E.C. Dijkmans, J.H. Huijsing
2001 IEEE Journal of Solid-State Circuits  
A dynamic element matching (DEM) algorithm is presented that is controlled by the quadrature output data of a complex sigma-delta modulator. This DEM technique is used to correct the gain and phase errors between the circuits in the in-phase and quadrature-phase feedback paths of the modulator. The key feature of this DEM technique is that it does not cause leakage of high-frequency quantization noise in the signal band, as encounters with the periodic or pseudorandom DEM techniques. No test
more » ... hniques. No test signal is required to measure the gain and phase errors, and as the DEM circuit is operating continuously, it compensates for changes in, e.g., temperature and supply voltage. A 0.35-m CMOS prototype chip has been designed to test the DEM circuit. A batch of 38 measured samples shows a typical mismatch-independent image rejection ratio of 63 dB with DEM.
doi:10.1109/4.972138 fatcat:5geuxbcmvvgtdpcezl6zdrvqse