Patent ID: 7061845
Filing Date: 2006-06-13
Classification: G11B

Abstract:
1. A write clock generation circuit for generating write clock from wobble signal based on a wobbling track formed on a recording medium, comprising: two variable gain amps that amplify respective signals from a photo detector divided into two portions by a dividing line in a tangential direction of the track at a determined gain; a gain control circuit that determines the gain of said variable gain amps in a particular period immediately after the beginning of data-writing by varying the gain of said variable gain amps stepwise; a subtractor that produces wobble signal by subtracting outputs from said respective variable gain amps; a wobble amplitude regulation AGC circuit that automatically controls gain thereof so as to regulate amplitude of the wobble signal output therefrom; a making-binary circuit that digitizes signals output from said wobble amplitude regulation AGC circuit into made-binary wobble signal; and a PLL circuit that generates write clock using the made-binary wobble signal as a reference.