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:
Apr. 26, 1994
Filed:
Jul. 01, 1992
Thomas A Asprey, Boulder, CO (US);
Hewlett-Packard Co., Palo Alto, CA (US);
Abstract
An integrated circuit output driver circuit is disclosed. The output driver varies the impedance of the driver circuit based upon the output voltage level present on the output pad. In that manner, the output driver circuit compensates for process variations and operating conditions. Two FETs are used in parallel to pull the voltage level of the output pad down. One FET is turned on and left on whenever a low voltage level in the output pad is desired. The other smaller FET is used to vary the total impedance of the driver by using feedback from the signal pad to sense when the pad voltage has reached a threshold level at that point the second FET is turned off.