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:
Sep. 03, 1985
Filed:
Sep. 24, 1982
Neil L Brown, Bourne, MA (US);
Neil Brown Instrument Systems, Inc., Cataumet, MA (US);
Abstract
A two-stage band-pass amplifier filter circuit which uses a bi-quad amplifier in each stage, the bi-quad amplifier being connected between an AC feedback amplifier in the signal transmission path and ground. The bi-quad amplifiers each provide a variable impedance and effectively operate as series-resonant circuits such that, during closed loop operation, the overall amplifier-filter circuit has a high gain at or near resonance and a very low gain off-resonance and has a phase shift of 0.degree. at resonance and .+-.90.degree. substantially off-resonance. The bi-quad amplifiers are connected to the feedback resistance of the signal path amplifier via a coupling resistance, the signal path amplifier feedback resistance being greater than the coupling resistance, normally by a factor as high as 20 to 1, so that the bi-quad amplifier is thereby prevented from overloading during operation.