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:
Sep. 19, 2000
Filed:
Sep. 17, 1997
Baker Scott, Austin, TX (US);
Izumi Kawata, Kanagawa, JP;
Crystal Semiconductor Corporation, Austin, TX (US);
Abstract
A high resolution variable time delay circuit is disclosed. In one embodiment, a current digital to analog converter (DAC) is used to sequentially charge two capacitors having similar capacitance construction. A threshold level capacitor provides the threshold level to a comparator, and a ramping capacitor is used for ramping to the threshold to provide a delay time. The comparator provides a delayed pulse using the threshold level provided by the threshold level capacitor and the ramp provided by the ramping capacitor. Thus, resolution is better than that provided by digital elements alone. This circuit also automatically cancels errors due to capacitance variations and unit current variation of the DAC introduced during the manufacturing process. In another embodiment a single capacitor is used in combination with two current DACs and a comparator to provide a controllable time delay.