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. 01, 2009
Filed:
Aug. 03, 2007
Stephen D. Wyatt, Jericho, VT (US);
Tian Xia, Essex Junction, VT (US);
Stephen D. Wyatt, Jericho, VT (US);
Tian Xia, Essex Junction, VT (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
Disclosed are current sink and source circuits, a charge pump that incorporates them, and a phase locked loop that incorporates the charge pump. The current sink and source circuits each have a current mirror that biases a transistor connected to an output node. These circuits each further have a two-stage feedback amplifier to sense the current mirror drain voltage and to control the transistor gate voltage in order to stabilize the current mirror drain voltage independent of output voltage at the output node. The amplifier also increases output resistance at the output node. This configuration allows for a wide operation voltage range and ensures good circuit performance under a very low power supply. A charge pump that incorporates these circuits generates highly matched charging and discharging currents. A PLL that incorporates this charge pump exhibits minimal bandwidth shifts and minimal locking speed and jitter performance degradation.