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. 30, 1999
Filed:
Oct. 08, 1997
Mohammad J Navabi, Austin, TX (US);
Cypress Semiconductor Corp., San Jose, CA (US);
Abstract
A driver circuit is presented which can transition between output voltage levels at a high switching speed. The preferred output driver is a PECL driver having both a correction circuit portion and a drive circuit portion. The correction circuit senses changes in the base-to-emitter forward bias voltage V.sub.BE of drive transistors within the drive circuit. Thus, any change in performance of those drive transistors is replicated in the correction circuit, which then produces a compensating current. The compensating current is modulated by a reference voltage value, and mirrored to the drive circuit. The drive circuit includes not only differential input transistors and differential drive transistors, but also a resistor coupled to the base terminal of each drive transistor. The resistor receives the compensating current which then offsets any change in voltage level (V.sub.OH or V.sub.OL) produced at the output of the drive transistors. The compensating current and specifically the compensating current as reflected upon the drive transistor outputs offset any dependence upon the forward bias voltage of the drive transistor caused by, for example, temperature or fabrication skews.