Oversampling parallel delta-sigma modulator A/D conversion

摘要

Conventional delta-sigma analog-to-digital convertersn(ΔΣADC's) are widely used in low-bandwidth applications suchnas high-fidelity audio processing because they offer high-precisionnconversion yet are amenable to implementation using fine-line VLSInprocesses optimized for digital circuitry. However, their oversamplingnrequirement so far has prevented their widespread application to highernbandwidth applications such as video processing. This paper extends anrecently developed delta-sigma ADC architecture called thenpi-delta-sigma ADC (ΠΔΣADC) that consists of multiplenΔΣ modulator channels operating in parallel withoutntime-interleaving. The extension developed in this paper allows fornoversampling to be combined with parallelism such that an M-channelnsystem with an oversampling ratio of N can achieve a conversionnperformance close to that of a conventional ΔΣADC with annoversampling ratio of M×N. Thus, for a given conversion precision,nthe architecture offers relaxed oversampling relative to conventionalnΔΣADCs in return for increased analog circuit area.nMoreover, as will be shown, the ΠΔΣADC retains much ofnthe robustness of conventional ΔΣADC's with respect tonnonideal circuit behavior