Robust delta-sigma modulators based on variable-structure control

We present a new delta-sigma modulator architecture based on variable-structure control theory. Our approach augments the conventional modulator design with switchable feedback gains and complementary logic. Stability is proved for arbitrary-order continuous-time loop filters in the idealized case of infinite sampling rate, under moderate assumptions. The proposed design achieves the peak performance of comparable traditional modulators and is also more robust, as shown in simulations. Our approach accommodates multi-level quantization, a dither signal channel and suggests a low-cost hardware implementation.