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:
Apr. 01, 1976
Shin-ichi Ohashi, Toyokawa, JA;
Akihiro Asada, Kodaira, JA;
Hitachi, Ltd., , JA;
Abstract
A variable impedance circuit comprises an amplifier with a high input impedance and a high output impedance whose gain is variable in response to a control voltage, an emitter-follower transistor, and an impedance element adapted to feedback an output signal to an input terminal of the amplifier. The input terminal of the amplifier and the input terminal of the emitter-follower transistor are connected in common. The emitter-follower transistor has its output terminal connected in series with the output terminal of the amplifier through a load resistor. An impedance of the amplifier as viewed from its input terminal is multiplied by Miller effect and varied in value by the control signal to a great extent.