Embedded sar based active gain capacitance measurement system and method

A method for measuring a capacitance of a first capacitor, comprising:

• (a) precharging first terminals of at least one of a plurality of weighted CDAC capacitors, respectively, of a CDAC (capacitor digital-to-analog converter) included in a SAR (successive approximation register) converter to a first reference voltage during a precharge phase, and precharging a first terminal of the first capacitor to a second reference voltage during the precharge phase;
• (b) coupling the first terminals of the CDAC capacitors to the first terminal of the first capacitor to redistribute charges among the first capacitor and at least some of the plurality of feedback capacitors during a measurement phase after the precharge phase so as to generate a first voltage on a measurement conductor;
• (c) amplifying the first voltage by means of an amplifier having a feedback network including the CDAC to generate a second voltage on an output of the amplifier during the measurement phase while coupling at least some of the first terminals of the CDAC capacitors to the second voltage, the first voltage being representative of the capacitance of the first capacitor;
• and
• (d) performing a successive approximation conversion operation on the second voltage during a conversion phase after the measurement phase to generate a digital representation of the first capacitance.

A capacitance measurement system for measuring a capacitance of a first capacitor, comprising:

• (a) means for precharging first terminals of at least one of a plurality of weighted CDAC capacitors, respectively, of a CDAC (capacitor digital-to-analog converter) included in a SAR (successive approximation register) converter to a first reference voltage during a precharge phase, and precharging a first terminal of the first capacitor to a second reference voltage during the precharge phase;
• (b) means for coupling the first terminals of the CDAC capacitors to a first terminal of the first capacitor to redistribute charges among the first capacitor and at least some of the plurality of CDAC capacitors during a measurement phase after the precharge phase so as to generate a first voltage on a measurement conductor;
• (c) amplifying means for amplifying the first voltage having a feedback network including the CDAC to generate a second voltage on an output of the amplifier during the measurement phase while coupling at least some of the first terminals of the CDAC capacitors to the second voltage, the first voltage being representative of the capacitance of the first capacitor;
• and
• (d) means for performing a successive approximation conversion operation on the second voltage during a conversion phase after the measurement phase to generate a digital representation of the first capacitance.