Circuit for capacitance measurement and method therefor

A capacitance measurement circuit, the circuit comprising:

• an integrator circuit having an input end and an output end, wherein the output end has an integrated voltage, and the integrator circuit, in response to a control signal, sets the integrated voltage to a start voltage level in a voltage setting period;
• a first control circuit comprising a first output end and a passive device, wherein the passive device has a known characteristic parameter, the first output end is electrically coupled to the input end, the first control circuit switches a voltage on at least one end of the passive device in response to a first set of clock signals, and selectively enables one end of the passive device to be electrically coupled to the first output end so as to control the integrator circuit to perform voltage integration and adjust a level of the integrated voltage from the start voltage level to an end voltage level in a first integration period;
• a second control circuit comprising a second output end and a to-be-measured capacitor, wherein the second output end is electrically coupled to the input end, and the second control circuit switches a voltage on at least one end of the to-be-measured capacitor in response to a second set of clock signals, and selectively enables one end of the to-be-measured capacitor to be electrically coupled to the second output end so as to control the integrator circuit to perform the voltage integration and adjust the integrated voltage from the end voltage level to the start voltage level in a second integration period, wherein a capacitance of the to-be-measured capacitor is relevant to a difference between the end and start voltage levels;
• and
• a processor circuit for providing the first and second sets of clock signals to drive the first and second control circuits, and for measuring the capacitance of the to-be-measured capacitor according to time lengths of the first and second integration periods and the known characteristic parameter.

A capacitance measurement method applied to a capacitance measurement circuit, the measurement circuit comprising an integrator circuit, one output end of the integrator circuit having an integrated voltage, a to-be-measured capacitor being electrically coupled to an input end of the integrator circuit, the measurement method comprising the steps of:

• (a) switching a voltage on at least one end of the to-be-measured capacitor in response to a first set of clock signals so as to adjust a level of the integrated voltage from a start voltage level to an end voltage level in a first integration period;
• (b) adjusting the level of the integrated voltage from the end voltage level to the start voltage level in a second integration period in response to a second set of clock signals;
• and
• (c) determining a capacitance of the to-be-measured capacitor according to the first and second integration periods and a known characteristic parameter.

A capacitance measurement method applied to a capacitance measurement circuit, the measurement circuit comprising an integrator circuit, one output end of the integrator circuit having an integrated voltage, a to-be-measured capacitor being electrically coupled to an input end of the integrator circuit, the method comprising the steps of:

• (a) adjusting the integrated voltage from a start voltage level to an end voltage level in a first integration period in response to a first set of clock signals;
• (b) switching a voltage on at least one end of the to-be-measured capacitor in response to a second set of clock signals so as to adjust a level of the integrated voltage from the end voltage level to the start voltage level in a second integration period;
• and
• (c) determining a capacitance of the to-be-measured capacitor according to the first and second integration periods and a known characteristic parameter.