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:
Nov. 15, 2005
Filed:
Apr. 22, 2003
Hiroshi Sakamoto, Tokyo, JP;
Tsukasa Hoshi, Sendai, JP;
Hiroshi Sakamoto, Tokyo, JP;
Tsukasa Hoshi, Sendai, JP;
Freescale Semiconductor, Inc., Austin, TX (US);
Abstract
A light-emitting element drive circuit capable of controlling the drive current of a light-emitting element in consideration of changes in a threshold value of the light-emitting element. A laser diodeemits light in accordance with a bias current Ib of a bias current drive circuitand a light-emitting current Ip of a data current drive circuit. A photodiodeoutputs a monitor current Im that corresponds to the optical output of the laser diode. A bias current feedback circuitdetects a change in the threshold current in accordance with the current Im, and outputs a control signal CS. The bias current drive circuitgenerates a bias current Ib that corresponds to the threshold current Ith of the laser diodeafter the change. A light-emitting current feedback circuitdetects a change in the optical output of the laser diodein accordance with the current Im, and outputs a controls signal CS. The data current drive circuitgenerates a light-emitting current Ip relative to a pre-determined optical output of the laser diodein accordance with the control signal CS