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:
Dec. 02, 2003
Filed:
Apr. 02, 2002
Peter F. Chu, Poway, CA (US);
Northrop Grumman Corporation, Los Angeles, CA (US);
Abstract
A rail-to-rail charge pump circuit ( ) that provides a current source and a current sink to a loop filter ( ). The circuit ( ) is responsive to two differential logic signals from a phase comparator ( ) that compares the phase of a divided down voltage controlled oscillator signal to a reference signal. The charge pump circuit ( ) employs complimentary pairs of PNP and NPN bipolar transistors. One of the input signals from the phase comparator ( ) is applied to the base terminal of a bipolar transistor ( ) that generates a mirror current in another bipolar transistor ( ) to provide the source current. The other input signal from the phase comparator ( ) is applied to the base terminal of a bipolar transistor ( ) that generates a mirror current in another bipolar transistor ( ) to provide the sink current. A bleed resistor ( ) is coupled to the base terminal of the bipolar transistor ( ) so that the circuit ( ) always provides a constant phase comparator gain.