Patent ID: 7688692

Claim:
An optical storage apparatus, comprising: a pickup head for receiving a beam reflected from an optical disc to generate a plurality of radio frequency (RF) signals; a preamplifier, coupled to the pickup head, the preamplifier comprising: a signal adjusting apparatus, having a plurality of input terminals for receiving the RF signals, at least two of the input terminals of the signal adjusting apparatus being substantially short-circuited when the optical storage apparatus is in a calibration mode; a phase detector, coupled to the signal adjusting apparatus, the phase detector generating a plurality of control signals based on the phase differences between the radio frequency signals; a charge pump, coupled to the phase detector, the charge pump comprising a plurality of current sources and a plurality of switches coupled to the current sources, the switches being controlled by the control signals to generate a tracking error signal; and a circuit, coupled to the charge pump, the circuit generating at least one current control signal based on the tracking error signal when the optical storage apparatus is in the calibration mode, the current magnitude of at least one of the current sources being determined according to the current control signal; and a servo control, being coupled to the preamplifier and receiving the tracking error signal.