Patent ID: 6366549
Filing Date: 2002-04-02
Classification: G11B

Abstract:
A circuit for detecting a mirror signal from an output signal of an RF (radio frequency) amplifier for amplifying a signal picked up from a disk of an optical disk drive with a radio frequency, comprising:a first peak hold circuit for holding a peak value of the output signal of said RF amplifier to provide a first peak value; a first bottom hold circuit for holding a bottom value of the output signal of said RF amplifier to provide a first bottom value; a differential amplifier for amplifying a difference between said first and second peak values; a second peak hold circuit for holding a peak value of an output signal of said differential amplifier to provide a second peak value; a second bottom hold circuit for holding a bottom value of the output signal of said differential amplifier to provide a second bottom value; a centered value extractor for processing said second peak and second bottom values to extract a centered value of the output signal of said RF amplifier; a first comparator for comparing said centered value with the output signal of said differential amplifier to generate said mirror signal; and a hold time constant adjustment circuit connected between said centered value extractor and said second peak and second bottom hold circuits to adjust time constants of said second peak and second bottom hold circuits according to a change in a level of the output signal of said RF amplifier.