Parametrically controlled noise shaping in variable state-step-back pseudo-Trellis SDM

Progress is reported in parametrically controlled noise shaping sigma delta modulator (SDM) design. As this SDM structure can provide a higher SNR than normal SDM structures, Philips Research Laboratories questioned whether further improvement could be obtained using techniques inspired by the Trellis SDM. Simulations are used here to illustrate the performance of a parametrically controlled pseudo-Trellis SDM. The technique uses uniquely a variable state step-back approach to mediate loop behaviour that is shown to achieve robust stability in the presence of aggressive noise shaping and high level signals. Comparisons are made with traditional SDM structures and LPCM systems for high-resolution audio applications.