A Capacitance-to-Digital Converter with Differential Bondwire Accelerometer, On-chip Air Pressure and Humidity Sensor in 0.18 μm CMOS

This paper presents a sensor front-end for air pressure sensor, relative humidity (RH) sensor, and accelerometer in a standard CMOS process. For air pressure and RH, interdigitated top metals in air and polyimide are exploited respectively, which exhibit the change in dielectric constant. For acceleration, separation among three bondwires is exploited. These sensing transducers induce capacitance change that is quantized by a CDC based on a dual quantization architecture that employs a single-bit 1st-order $\Delta\sum$ modulator and a 7-bit SAR ADC.