A low-power 12-bit capacitance-to-digital converter for capacitive MEMS pressure sensor

A novel low-power capacitance-to-digital converter (CDC) switched-capacitor is presented. The proposed CDC is targeted to work with MEMS capacitive pressure sensors that exhibit a large fixed capacitive component and a small variable capacitive component. The proposed CDC works by subtracting the large fixed capacitive component first and converting to time the remaining capacitance. The time equivalent is then digitized using a counter. The designed CDC consumes 90 μW of power and has a resolution of 12 bits making it suitable for energy-constrained applications such as implantable sensors. The designed CDC was implemented on a 0.5 μm CMOS technology with the die measuring 3 mm × 2.4 mm.