A Full 12-Bit Switched-Current ΔΣ Modulator with Self-Calibration

In this paper we present a differential switched-current delta-sigma modulator achieving full 12 bit resolution. A differential first generation based S2I cell is adopted for its superior linearity, while the use of an efficient self-calibrating technique minimizes integrator loss due to its poor transistor matching. Measurement results on a first-order prototype show a 74 dB signal-to-distortion ratio. The complete circuit occupies 0.25 mm2 of silicon area in a 0.8 μm DPSM CMOS process.

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