Design Considerations of MASH ΔΣ Modulators with GRO-based Quantization

A gated ring oscillator (GRO) based multi-stage noise-shaping ΔΣ modulator (Δ∑M) is presented in this paper. Loop-filter integrators followed by a digitally implemented GRO make the proposed architecture suitable for scaling-friendly implementations. Quantization noise of the first stage is represented in the time domain and it eases the quantization error extraction with a simple digital circuitry. The GRO offers inherent dynamic element matching, and hence no extra circuitry is needed to linearize the DACs in the feedback path. Time-domain behavioral simulations are shown to study of main GRO non-idealities considering a discrete-time MASH 3–1 topology, featuring a SNDR of 94 dB for an OSR of 16 over a 2-MHz signal bandwidth.

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