Wideband Continuous-Time MASH ADCs: Principles, Challenges, and Prospects

Continuous-time (CT) delta-sigma modulator (DSM) is a popular choice for its inherent aliasing and resistive input impedance characteristics. With the increased demands for wide-bandwidth (BW) and high-dynamic range (DR), multistage noise shaping (MASH) presents prominent benefits of high-order noise-shaping (NS) without being constrained by $\Delta \Sigma $ loop stability issues. Recent literature on CT MASH DSM showed promising progress in overcoming the design challenges under wideband application, including signal and quantization leakage, analog-digital matching complexity, signal transfer function (STF) peaking, and high-speed excess loop delay (ELD) compensation. This review article introduces fundamental models and primary design considerations, then discusses the CT MASH DSM’s key challenges and corresponding solutions. Finally, we provide two implementation examples of this architecture with their highlights and challenges.