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:
Jul. 14, 1998
Filed:
Sep. 03, 1996
Jozef B Baran, Irvine, CA (US);
AST Research, Inc., Irvine, CA (US);
Abstract
A termination circuit for RGB signal lines provides a high frequency termination impedance that matches the impedance of a monitor cable and monitor termination, without adversely affecting the monitor-sense circuitry of an ASIC that generates the RGB video signals. The termination circuit includes a first resistor connected in parallel with a diode. The diode is reversed biased when a DC voltage is present on a VGA line. The parallel circuit is connected in series with a second resistor such that at DC the termination circuit has a resistance equal to the sum of the resistances of the two resistors. At high frequencies the termination circuit has a resistance equal to the second resistor. When used with a VGA ASIC designed to work with 150.OMEGA. pull-down sense resistors on the RGB lines, the circuit provides the proper 75.OMEGA. AC termination impedance required for VGA lines while producing the 150.OMEGA. DC termination required for proper monitor sense operation.