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:
Nov. 14, 2000
Filed:
Jul. 08, 1999
Masaharu Ikeda, Yokohama, JP;
Masayoshi Esashi, Sendai, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
A guard electrode is formed on a frontside surface of a semiconductor substrate and a fixed electrode is formed on the guard electrode via an insulating layer. A cavity is formed on the fixed electrode by a diaphragm and a moving electrode is formed between the layers of the diaphragm. A substrate through hole directing from a backside surface of the substrate and reaching the cavity is formed. An operational amplifier which drives the guard electrode so as to equalize an electric potential of the guard electrode with that of the fixed electrode is provided. A change in the capacitance between the fixed electrode and a moving electrode is converted into a voltage directly concerned with a displacement of the diaphragm.