The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 07, 2003
Filed:
Mar. 10, 2000
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
A tracking error balance adjustment circuit, and a current control circuit used for a variable gain RF amplifier automatically controlled to output a signal having a predetermined amplitude. The tracking error balance adjustment circuit comprises two separate gain adjusting circuits, each having variable attenuation circuit having first gm amplifier of variable gm type, a second gm amplifier of variable gm type connected to the variable attenuation circuit, and an output circuit connected to the second gm amplifier, comprising an operational amplifier circuit having feedback resistor, wherein the first and second gm amplifiers are differentially controlled commonly by a control current. The a current control circuit is arranged in a variable gain RF amplifier connected to a head amplifier circuit amplifying an output signal from optical pickup, controlling a current output of the variable gain RF amplifier so that it changes in accordance with different functions in the range where the control voltage input is lower than the reference potential and the range where the control voltage input is higher than the reference potential, with the result that the gain control sensitivity can be set almost equal between the two ranges.