Patent ID: 7957634

Claim:
A circuit for calibrating a focus position of an optical module, comprising: a calibration signal generating unit, for generating a calibration signal according to at least a first focus signal and a second focus signal at the same time, where the first and second focus signal correspond to a first and a second focus positions, respectively, and the first focus position is different from the second focus position; and a focus position adjusting unit, coupled to the calibration signal generating unit, for adjusting the focus position of the optical module to a specific focus position according to the calibration signal; wherein the calibration signal generating unit comprises: a comparator, for comparing the first focus signal and the second focus signal to generate a comparing signal; a filter, coupled to the comparator, for filtering the comparing signal to generate a filtered comparing signal; and an integrator, coupled to the filter, for generating the calibration signal according to the filtered comparing signal.