Oversampling sigma-delta modulator stabilized by local nonlinear feedback loop technique

The proposed scheme relates to a technique called “local nonlinear feedback loop (LNFL)” for stabilization of oversampling sigma-delta modulators (SDMs). SDM stabilized by the LNFL technique avoids the instability limitation without overall signal-to-noise ratio (SNR) degradation, because the LNFL technique keeps the input dynamic range within proper bounds (-Δ/2, Δ/2) absolutely to prevent integrators from overload, whether the critical integrator in SDM enters the unstable region or not. Unlike conventional methods, the nonlinear compensative operation in the proposed technique does not increase the quantization noise proportionally to cause the overall SNR degradation in the meanwhile. Besides, the proposed algorithm can be applied to various configurations of oversampling SDMs, such as single-loop and multiple-loop structures, for high stability and low-power very large scale integration applications