Capacitance-to-digital converter based on power detection

High resolution capacitance-to-digital converters (CDC) usually have severe capacitance range limitations or high power consumption. This paper presents a power detection based 16-bit CDC with a maximum capacitance range superior to 1 nF and a capacitance resolution as small as 0.27 fF. This work´s multi-stage power detector provides the CDC with three different sensitivity rates making it highly versatile. An on-chip low-pass filter was added to prove the method´s reliability for on-chip applications. The circuit was designed using a 0.25-μm CMOS technology, operates at a single 2.5-V supply, and consumes less than 1.86 mW.