Patent ID: 8736389

Claim:
A calibration circuit of a frequency generator, the calibration circuit comprising: at least two compensation circuits coupled to an input signal for outputting at least a first compensation signal and a second compensation signal, respectively, wherein the at least two compensation circuits comprise a first compensation circuit and a second compensation circuit, the first compensation circuit comprising: a zeroth-order compensation unit coupled to the input signal for outputting a zeroth-order compensation signal; a first-order compensation unit coupled to the input signal for outputting a first-order compensation signal; and a first adder coupled to the zeroth-order compensation signal and the first-order compensation signal for generating the first compensation signal; and the second compensation circuit comprising: an Nth-order compensation unit coupled to the input signal for outputting an Nth-order compensation signal acting as the second compensation signal, wherein N is a positive integer greater than 2; and a comparator coupled to the first compensation signal and the second compensation signal for outputting a calibration signal, wherein the calibration signal is used for determining an oscillation frequency of a crystal oscillator of the frequency generator in an open loop.