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. 24, 1993
Filed:
Oct. 17, 1991
Applicant:
Inventors:
Ian G Fobbester, Gloucestershire, GB;
Peter Good, Wiltshire, GB;
Assignee:
Primary Examiner:
Int. Cl.
CPC ...
H02M / ; H03L / ;
U.S. Cl.
CPC ...
363 60 ; 307510 ; 307511 ; 328155 ; 323315 ;
Abstract
A charge pump circuit for a frequency/phase comparator in a phase locked loop oscillator arrangement, in which current sources utilizing only npn transistors provide currents of equal magnitude but of opposite sense to an input of an operational amplifier, the output of this amplifier charge-pumping a capacitor to control the frequency of oscillation of an oscillator. The use of npn transistors enables higher current levels and higher speed switching compared to circuits including pnp transistors.