Patent ID: 7009429

Claim:
A circuit for a frequency reference in an integrated circuit using a MOSFET as a stable capacitor, comprising a constant current source; switching means charging and discharging said MOSFET capacitor being activated periodically by the output of a comparing means; said comparing means having an input and an output wherein the input is the voltage of said MOSFET capacitor and a voltage exceeding the threshold voltage of said MOSFET capacitor to influence the frequency and the amplitude of the output of said comparing means and the output is a periodical pulse; said MOSFET capacitor being charged/discharged periodically by said constant current source and its voltage level being the input to said comparing means and its threshold voltage is used to compensate the variations of its capacitance; means to provide a voltage exceeding the threshold voltage of said MOSFET capacitor to influence the frequency and the amplitude of the output of said comparing means; and means to transform the periodical pulse into an alternating clock signal to drive said switching means and being the output of said frequency reference circuit.