Embedded SAR based active gain capacitance measurement system and method

摘要

A system for measuring a capacitor (C_SENj) precharges a CDAC (23) in a SAR converter (17) to a reference voltage (V_AZ) and also precharges a first terminal (3-j) of the capacitor to another reference voltage (GND). During a measurement phase, the CDAC is coupled between an output and an input of an amplifier (31) and the capacitor also is coupled to the input of the amplifier, so as to redistribute charge between the capacitor and the CDAC. The amplifier generates an output voltage (V_AMP) representing the capacitance being measured. The output voltage is stored in the CDAC. The SAR converter converts the output voltage to a digital value representing the capacitance being measured.