Frequency-current conversion circuit, equalizer, and optical disc apparatus

Abstract

A frequency-current conversion circuit permits stabilization of the frequency characteristic of an equalizer that is used in a high-speed optical disc apparatus. The frequency-current conversion circuit includes a comparison circuit that includes a first capacitor that is charged by an output reference current and is forcibly discharged over a predetermined period from the change point of the input clock of the input clock terminal, and that compares the voltage produced in the first capacitor with a reference voltage, a charging / discharging circuit that includes a second capacitor that is charged and discharged in accordance with the output of the comparison circuit and that outputs a voltage that is produced in the second capacitor, a sample and hold circuit that samples and holds the output voltage of the charging / discharging circuit within the predetermined period, and a voltage-current conversion circuit that converts the held voltage to the output reference current and an output current that is proportional to the output reference current.

Description

technical field [0001] The present invention relates to a frequency current conversion circuit which generates an output current corresponding to the frequency of an input clock, an equalizer comprising the frequency current conversion circuit and having a steep frequency characteristic, and an equalizer comprising the equalizer CD device. Background technique [0002] Optical disk devices have such image 3 The basic structure of the signal processing block is shown. That is to say, the optical disc device 1 detects optical signals according to code points in an optical disc 9 such as a compact disc (CD) or a digital versatile disc (DVD) by means of a photoelectric sensor 10, amplifies the detected signal by an RF amplifier 11, and This signal (differential RF signal) is corrected by the equalizer 12 . Then, the optical disc device 1 binarizes the corrected signal through a slicer 13 , and then demodulates (reproduces) digital data from the binary signal through a demodul...

AI Technical Summary

Problems solved by technology

However, when the speed of the optical disc device changes, it is difficult for the potential of node D to follow the change in the frequency of the input clock with proper timing.

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