Noise shaping advantages of band-pass multi-step look-ahead sigma-delta modulators over conventional ones in signal synthesis

Abstract

Sigma-Delta modulators (SDMs) are capable of shaping the quantization noise out of a specific frequency band defined by their noise transfer function (NTF). A single-bit output SDM pose further advantages in applications that would typically require a multi-bit DAC, since then only a single-bit DAC is required, which is much easier to design and is inherently linear in comparison to a multi-bit one. Look-ahead SDMs have been proposed to enhance the signal-to-noise-and-distortion-ratio (SNDR) and the output bandwidth of conventional single-bit SDMs. Multi-Step Look-Ahead sigma-delta modulators (MSLA SDMs) further reduce the hardware complexity required for the implementation of typical look-ahead SDMs while maintaining their performance advantages. In this work the architecture and the benefits of the MSLA SDMs are showcased. Finally the advantages of the MSLA SDMs over single-bit conventional ones are demonstrated and several hardware implementation choices for design optimization are discussed.