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. 09, 1994
Filed:
Dec. 14, 1992
Applicant:
Inventors:
John S French, Arlington Heights, IL (US);
Richard W Peters, Algonquin, IL (US);
Assignee:
Knowles Electronics, Inc., Itasca, IL (US);
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H03F / ;
U.S. Cl.
CPC ...
330258 ; 330156 ; 330300 ; 330311 ; 381120 ;
Abstract
A tiny pre-amplifier for a small, low voltage, high impedance signal source, usually an electret microphone, exhibiting near unity gain, has an input cascode stage connected to the microphone and a matched balancing cascode stage; both cascode stages are energized from the same power supply circuit. The two cascode stages supply intermediate signals to the inputs of a differential amplifier to generate an output signal having a greatly reduced noise content, independent of power supply variations. The pre-amplifier is wholly integratable, has low power drain, and fits into the microphone housing.