Comparison of sigma-delta converter circuit architectures in digital CMOS technology
Integration of analog-to-digital signal conversion circuits into digital submicron silicon chips is required for many applications. This is typically implemented by sigma-delta circuits, which can provide good resolution without requiring trimming of component values. This paper presents an analytical comparison of noise performance in four alternative sigma-delta circuit configurations which have been presented in the literature, consisting of discrete-time and continuous-time integration in voltage-mode and in current-mode. For high resolution, superiority of switched-capacitor circuits over the alternatives is shown, based on process technology considerations. Design guidelines are outlined for selecting oversampling rate and other key parameters, in order to obtain maximal data resolution.
analog-digital conversion sigma-delta modulation signal-to-noise analysis low voltage cmos switched capacitors switched current