Fundamentals of Continuous-Time ADCs: Part Two: Continuous-Time Delta–Sigma Converters

The first part of this two-article series described the continuous-time pipelined (CTP) ADC, which is appropriate when the oversampling ratio (OSR) is small. When the OSR is large, it becomes feasible to embed the quantizer into the antialias filter’s feedback loop. Such sub-systems are referred to as continuous-time delta-sigma modulators. This article describes the ideas behind such analog-to-digital converters.