A Low-Power Auto-Zero Switched-Capacitor Dual-Slope Noise-Shaping Direct CDC

A noise-shaping dual-slope based complete Switched-Capacitor (SC) direct Capacitance-to-Digital Converter (CDC) for differential sensors has been proven on silicon. The proposed topology does not need a pre-amplifier to interface the sensor. Direct SC sensor readout and single-bit circuitry show to be very area efficient. A SC single-bit capacitive DAC is used during digitization. Auto-zeroing is implemented within the complete SC approach of an inherently robust dual-slope converter. Additionally, quantization noise-shaping reduces the measurement time. A prototype is realized in 0.13µm CMOS technology. A 3.2ms measurement results in 13bit resolution while consuming 35µA from a 1.5V supply occupying 0.148mm 2.1