Patent ID: 8351311

Claim:
A semiconductor integrated circuit which is mounted on an optical disk device having an optical pickup, the semiconductor integrated circuit for receiving a first light reception output signal, a second light reception output signal, a third light reception output signal, and a fourth light reception output signal from four light receiving regions of a light receiving element of the optical pickup, the semiconductor integrated circuit comprising: a wobble signal generating circuit configured to detect a wobble in a recordable disk which is inserted in the optical disk device; a differential phase detecting method signal generating circuit for tracking an unrecordable disk which is inserted in the optical disk device; and an operation circuit comprising two A/D converters and an arithmetic circuit, wherein when a first operation mode is set, the operation circuit generates a first digital addition output signal based on the first and third light reception output signals and a second digital addition output signal based on the second and fourth light reception output signals by using output signals selectively supplied to the two A/D converters and the operation of the arithmetic circuit, wherein when a second operation mode is set, the operation circuit generates a third digital addition output signal based on the first and fourth light reception output signals and a fourth digital addition output signal based on the second and third light reception output signals by using output signals selectively supplied to the two A/D converters and the operation of the arithmetic circuit, wherein the wobble signal generating circuit generates a digital wobble signal by execution of digital subtraction operation using the third and fourth digital addition output signals generated in the second operation mode, and wherein the differential phase detection method signal generating circuit generates a digital phase comparison signal using the first and second digital addition output signals generated in the first operation mode.