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. 22, 2000
Filed:
Aug. 25, 1998
Stephen T Williams, Laurel, MD (US);
Eric Naviasky, Ellicot City, MD (US);
Michael Hufford, Catonsville, MD (US);
Cadence Design Systems, Inc., San Jose, CA (US);
Abstract
A charge pump having an automatic compensation capability comprises a current source and a current sink. The current source is selectively coupled to the output of the charge pump by a sourcing control. The sourcing control receives an input control signal and responds by controlling the sourcing current flowed from the current source to the output. Likewise, the current sink is selectively coupled to the output of the charge pump by a sinking control. The sinking control receives a second input control signal and responds by controlling the sinking current flowed from the output to the current sink. The charge pump further comprises a sensing circuit and a compensating circuit. The sensing circuit determines whether, given substantially identical input control signals, there is a difference between the sourcing current and the sinking current generated by the charge pump. If so, the sensing circuit provides at its output an indication of the current difference. In turn, the compensating circuit receives as input the indication of the current difference, and adjusts the sinking current in accordance with the indication of the current difference such that the sinking current equalizes the sourcing current. In an alternative embodiment, the compensating circuit adjusts the sourcing current rather than the sinking current to equalize the sourcing current with the sinking current. In either embodiment, a substantially zero net current is produced at the output of the charge pump when the input control signals are substantially identical.