A 1.95-V, 0.34-MW, 12-B SIGMA-DELTA MODULATOR STABILIZED BY LOCAL FEEDBACK LOOPS

The design of a low-power, low-voltage, 12-b 8-kHz bandwidth Sigma Del ta modulator for high-quality voice that consumes only 0.34 mW at 1.95 V supply is described, The modulator employs a special architecture i n which a third-order modulator is stabilized by a local feedback loop around each integrator, Unlike multistage Sigma Delta modulators, thi s architecture is very tolerant to the modest de gain of low voltage o p-amps. The architecture, together with special circuit techniques, pe rmits a low-voltage switched capacitor implementation at 1.95 V-3.3 V supply using standard 1.2-mu m CMOS technology.