Patent ID: 7821345

Claim:
A method of calibrating an oscillator to adjust the output frequency of the oscillator according to an oscillator control signal, the method comprising: comparing the frequency of a reference signal to be obtained at the output of the oscillator and the frequency of the output signal of the oscillator divided by a quantity; determining an impedance value to be connected to the oscillator from a set of impedances, each corresponding to a frequency deviation of the oscillator so as to modify the output frequency of the oscillator to make it match the reference frequency; and connecting the impedance to the oscillator, wherein determining the impedance value comprises: changing a counter-downcounter by a first number on each occurrence of at least one of a rising edge and a falling edge of the oscillator reference signal, changing the counter-downcounter by a second number on each occurrence of at least one of a rising edge and a falling edge of the output signal, the second number having a mathematical sign opposite of the first number, and determining the impedance value when the count value of the counter-downcounter exceeds a predetermined threshold value.