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. 02, 1977
Filed:
Jul. 29, 1975
Yasuo Nagahama, Hamamatsu, JA;
Abstract
In a bridge circuit consisting of diodes connected in each circuit branch in a forward direction from one of a pair of opposing terminals to another with a current flowing through these diodes, impedance between a second opposing pair of terminals varies in correspondence to the magnitude of the constant current. The invention utilizes this phenomenon and provides a voltage-controlled filter employing this bridge circuit as an impedance element for determining its frequency region and thereby being capable of controlling its frequency region by voltage controlling. A primary passive low-pass filter is described as a preferred example of the invention. The invention further provides a voltage-controlled filter having the bridge circuit provided in a negative feedback loop of an amplifier in an active filter circuit and thereby being capable of controlling selectivity Q by controlling the gain of the amplifier by voltage controlling. As a preferred example of this type of filter, a secondary active low-pass filter is described.