Method and related apparatus for deriving a tracking error signal

• US 7,345,964 B2
• Filed: 08/23/2006
• Issued: 03/18/2008
• Est. Priority Date: 04/07/2003
• Status: Active Grant

• Current Assignee: MediaTek, Inc.
• Original Assignee: MediaTek, Inc.
• Inventors: Cheng, Yuh
• Primary Examiner(s): Young; Wayne
• Assistant Examiner(s): HOFFNER, LINH NGUYEN
• Application Number:
  US11/466,459
• Publication Number:
  US 20060280064A1
• Time in Patent Office: 573 Days
• Field of Search: 369/44.25, 369/44.34, 369/44.41
• US Class Current: 369/44.25
• CPC Class Codes: G11B 7/0906 Differential phase difference systems
• CPC Class Codes: G11B 7/0943 Methods and circuits for performing mathematical operations on individual detector segment outputs

Abstract

A method for deriving a tracking error signal based on a first analog detection signal and a second analog detection signal. The method includes summing the first analog detection signal and the second analog detection signal to generate an analog sum signal. An analog delay device is utilized to delay the analog sum signal to be a delay signal. The delay signal is digitalized into a digital delay signal. The first analog detection signal and the second analog detection signal are respectively transformed into a first digital detection signal and a second digital detect signal. The tracking error signal is then generated utilizing a comparing operation among the digital delay signal, the first digital detect signal, and the first digital detect signal.

Claims

1. A tracking error signal generator comprising:

four signal processing ports for respectively providing a first analog detection signal, a second analog detection signal, a third analog detection signal, and a fourth analog detection signal;

four high-pass filters for filtering out low-frequency noise from the first analog detection signal, the second analog detection signal, the third analog detection signal, and the fourth analog detection signal;

four digitizers respectively electrically connected to the four signal processing ports for respectively transforming the first, the second, the third, and the fourth analog detection signals into a first digital detection signal, a second digital detection signal, a third digital detection signal, and a fourth digital detection signal;

two relays for respectively delaying and then digitizing the first analog detection signal and the third analog detection signal to obtain a first digital delay detection signal and a third digital delay detection signal; and

four comparators for respectively comparing the first digital delay detection signal with the first digital detection signal to generate a first digital comparing signal, comparing the first digital delay detection signal with the second digital detection signal to generate a second digital comparing signal, comparing the third digital delay detection signal with the third digital detection signal to generate a third digital comparing signal, and comparing the third digital delay detection signal with the fourth digital detection signal to generate a fourth digital comparing signal.

2. The tracking error signal generator of claim 1 wherein there is a time difference between the first analog detection signal, the second analog detection signal, the third analog detection signal, and the fourth analog detection signal.