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:
May. 25, 1993
Filed:
Jun. 12, 1992
Ho D Truong, San Jose, C;
Smos Systems, Inc., San Jose, CA (US);
Abstract
A system and method for reducing the amount of ground bounce in output buffer circuits. The invention includes a first control circuit to control the amount of time it takes for a pull-up FET to be turned on, and thus the amount of time it takes for an output signal of the output buffer circuit to transition from a low to a high state. The invention also includes a second control circuit to control the amount of time it takes to turn on a pull down FET and thus the amount of time it takes for the output signal of the output buffer circuit to transition from a high to a low state. First and second control circuits each include an additional FET for controlling the amount of current supplied to the pull-up and pull-down FET, respectively. Each additional FET is driven by a voltage reference signal which is above the threshold of the additional FET. Thus, the additional FET is not fully on or off, but introduces a resistance into the control circuit, thus decreasing the amount of current supplied to the pull-up and pull-down FETs. Since the current amount of current provided to the final output FETs is reduced, their turn-on time is slower and thus the switching time of output buffer circuit is increased. As a result, the magnitude of ground bounce introduced by the output buffer circuit according to the present invention is significantly reduced.