US Patent 7916054 K-delta-1-sigma modulator

A K-Delta-1-Sigma modulator filters or integrates (Sigma) the difference (Delta) between K-feedback paths and an input signal. By using K-feedback paths the topology enables sample rates that are K times the clock frequency of any one feedback path. The sigma block can be implemented in a number of ways including an active or passive integrator or a filter with specific characteristics. When implemented as an integrator, the sigma block is common to all the feedback paths, so that the modulation noise is pushed to a portion of the spectrum where it can be reduced by filtering. The delta block can be implemented in a number of ways including analog adders or switched capacitors.