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:
Jun. 13, 1989
Filed:
Nov. 22, 1988
John D Speake, Cambridge, GB;
U.S. Philips Corporation, New York, NY (US);
Abstract
A bandpass filter comprises a reactively intercoupled pair of parallel-resonant circuits (1, 2) to one of which a pair of signal input terminals (15, 16) are connected and to the other of which a pair of output terminals (17, 18) are connected. Tuning of the filter is accomplished by varying the capacitive component of each circuit by means of a tuning voltage applied to a further input (19). In order to compensate for the deviation from the optimum intercoupling which would otherwise occur with change of tuning frequency the capacitive component of each resonant circuit comprises at least three capacitors (5, 6, 7 and 8, 9, 10) in series, each set of three capacitors effectively forming a variable capacitive voltage divider. The two junction points of the three capacitors of each set are each connected to the corresponding junction point in the other set by means of a respective bidirectional reactive coupling (13 and 14 respectively).