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:
Aug. 12, 1997
Filed:
May. 30, 1995
Reuven Holzer, Herzlia, IL;
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A controlled-slope output buffer is furnished to reduce electro-magnetic interference (EMI) and ground bounce noise which commonly arises in output buffers in a VLSI chip. In the controlled-slope buffer, output current pulses are shaped to reduce higher frequency signal components. Corrective shaping of the electrical signals by the controlled-slope buffer is effective in reducing EMI emissions in a frequency range from 200 to 1000 MHz. Output signals of the controlled-slope output buffer have voltage slopes which are substantially the same as output signals generated by conventional output buffers. However, the controlled-slope output buffer generates output signals in which the shape of the current pulse is greatly improved for reducing EMI and ground bounce noise. In the controlled-slope buffers according to the present invention, current pulses have a triangular shape when they are drawn in the time domain. This shape of current pulse results in the lowest achievable time derivative for a given capacitive load. Current pulses having this shape also reduce ground bounce levels in an integrated circuit chip.