Analog-to-digital converter with built-in charge-based capacitance measurements

Abstract

An ADC with built-in charge-based capacitance measurements is described. An example includes a plurality of capacitors coupled in parallel to an input voltage at a common node, a plurality of drivers each coupled to a respective capacitor opposite the common node, a first switch coupled to the common node to couple the common node to a ground in response to a second clock signal from a timing generator, a second switch coupled to the common node to couple the common node to a reference voltage in response to a third clock signal from the timing generator, a successive logic circuit configured to control each driver to alternately drive the second clock signal to a selected capacitor or to couple the selected capacitor to ground, and measurement logic including a current sensor to measure a current through the common node and configured to determine a capacitance of the selected capacitor.