A Self-coupled DT MASH ΔΣ Modulator with High Tolerance to Noise Leakage

Abstract

This paper presents a self-coupled discrete time (DT) multi-stage noise shaping (MASH) ΔΣ modulator (DSM) with high tolerance to noise leakage for wideband applications. The output of the second loop is directly coupled into the input of the first quantizer while the signal transfer function of the second loop is selected as one-cycle delay. As a result, an extra first-order shaping function is generated for the first stage. With the help of such an additional first-order shaping function, the inherent noise leakage is significantly alleviated in the proposed DT MASH architecture. Therefore, this technique allows using low-gain operational amplifiers without trading the resolution loss. Mathematical analysis and further simulation results are provided to prove the effectiveness of the proposed MASH architecture and its high potential for wideband applications.