A general cascaded noise-coupled architecture for ΔΣ modulators with segmented quantization

This paper presents a general cascaded architecture for ΔΣ modulators with a high resolution quantizer. The proposed achitecture is improved from the recently published digital noise coupling technique, to achieve an additional order of noise shaping. The proposed architecture adopts the conventional noise-coupled ΔΣ technique and spits the outputs of the quantizer into MSB segment and LSB segment. The MSBs are directly fed to the modulator input and an auxiliary DAC for noise coupling. The LSBs are filtered and subtracted from the MSBs to produce the final output. The proposed technique maintains the full potential of the aggressive quantization on the performance of a ΔΣ modulator and does not suffer from the exponential growth of the DEM logic. Sensitivity of the proposed technique against various circuit nonidealities has been checked using analysis and simulation.