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:
Jun. 06, 2000
Filed:
May. 22, 1998
Brian C Miller, Ft. Collins, CO (US);
Hewlett Packard Company, Palo Alto, CA (US);
Abstract
The present invention is generally directed to a circuit and method for evaluating the timing relationship of electrical signals in an integrated circuit. In accordance with one aspect of the invention, a circuit is provided having a signal select circuit that is includes two or more inputs and one output. The signal select circuit (preferably a multiplexer) is configured to select one of the two or more input signals for evaluation and direct it to the output. A plurality of signal buffers are electrically cascaded to the output of the signal select circuit. Finally, a scan chain having a plurality of scan elements is disposed to acquire a state of electrical signals along the plurality of signal buffers. In accordance with another aspect of the invention, a method is provided for evaluating the timing relationship of electrical signals in an integrated circuit. In accordance with this inventive aspect, the method includes the steps of selecting a first electrical signal to be evaluated and discretizing the selected electrical signal into a plurality of signal values closely spaced in time. This 'discretizing' function is preferably achieved passing the selected signal through a plurality of cascaded delay or buffer elements, then loading the signal values output from each buffer element (at a given time instance) into a plurality of register elements. In this way, the register elements, collectively, contain a snapshot of the selected signal over a defined period of time. Finally, the method includes the step of evaluating the plurality of signal values.