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. 06, 2004
Filed:
May. 10, 2000
Peter Joseph Van Laanen, Boulder, CO (US);
Infineon Technologies North America Corp., San Jose, CA (US);
Abstract
A circuit ( ) for driving a laser diode ( ) includes a fixed current source ( ), a programmable current source ( ), a differential output driver ( ), a phase splitter ( ), and a ring oscillator ( ). The fixed current source ( ) is always coupled to the laser diode ( ) and supplies a few milliamperes (well below the current required to make the diode lase) in order to maintain forward voltage on the laser ( ). The programmable current source ( ) is alternately coupled to the anode ( ) and the cathode ( ) of the laser diode ( ) by the differential output driver ( ) in response to signals from the phase splitter ( ). The phase splitter ( ) changes phase at a frequency controlled by the ring oscillator ( ). According to a presently preferred embodiment, a 25% duty cycle in the ring oscillator ( ) keeps the laser diode ( ) ON for 75% of the time. The frequency of the laser diode ( ) is nominally 300-500 Mhz. The circuit ( ) of the invention is preferably implemented as an integrated circuit chip ( ) which is mounted in die form very close to the laser diode ( ) in a leadframe package ( ) together with all of the photodetectors ( ) needed for using the laser diode ( ) to read or guide the reading/writing of disks.