Patent ID: 7002421

Claim:
A method for creating a capacitor reference in integrated circuits comprising: providing an RC oscillator circuit, a constant current source, a frequency reference, circuit a phase detector and a capacitor, having switching parts for regulation, to become a reference capacitor; generate with said RC oscillator circuit a periodic signal with frequency f 1 ; generate with said frequency reference circuit a signal with frequency f 2 ; compare said frequency f 1 and frequency f 2 and regulate the capacitance of the capacitor of said RC oscillator using a closed feedback loop until f 1 equals f 2 ; calculate the capacitance of the reference capacitor using the equation C = a × c U ⁢ ⁢ r × k . wherein the parameters a, c and k are physical constants or integer numbers and Ur occurs from defining the reference level of the RC oscillator; and use the calculated capacitance as reference capacitance.