A wide dynamic range and fast update rate integrated interface for capacitive sensors array

A low-power CMOS capacitance-to-digital converter for capacitive sensors array is presented. It consists of a 16-channel MUX, a front-end with wide dynamic range for capacitance-voltage conversion and a novel voltage-pulses convertor. This novel circuit charges the measured capacitor indirectly and converts it into a proportional voltage, and then produces a 16-bits pulses-formed single-line output with multi-steps quantization method. The circuit can operate under 1.2V to 3.6V voltage supply for single battery application. The maximum input is 350pF with 0.75ms/ch update rate and 90μA power consumption when the operating clock is 100KHz. The chip has been design and fabricated in 0.18-μm 1P6M CMOS process with active area of 640×630μm².