A 0.5 V Continuous-Time ΣΔ Modulator

In this chapter an audio-band continuous-time (CT) ΣΔ modulator is presented as another example of true low voltage design without using low threshold devices or internal voltage boosting. A ΣΔ modulator has a higher level of design complexity than the circuit examples presented in the previous chapters. It requires a clocked comparator and feedback digital-to-analog converters (DAC) in addition to a loop filter of either continuous-time or discrete-time type.