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:
Oct. 21, 2008
Filed:
Aug. 03, 2004
Tsuyoshi Ohshima, Kouza-gun, JP;
Shigehisa Kurogo, Kouza-gun, JP;
Masayuki Ishikawa, Kouza-gun, JP;
Susumu Kurosawa, Kawasaki, JP;
Yuki Fujimoto, Kawasaki, JP;
Yasutaka Nakashiba, Kawasaki, JP;
Tsuyoshi Ohshima, Kouza-gun, JP;
Shigehisa Kurogo, Kouza-gun, JP;
Masayuki Ishikawa, Kouza-gun, JP;
Susumu Kurosawa, Kawasaki, JP;
Yuki Fujimoto, Kawasaki, JP;
Yasutaka Nakashiba, Kawasaki, JP;
Epson Toyocom Corporation, Tokyo, JP;
NEC Electronics Corporation, Kanagawa, JP;
Abstract
Deterioration in frequency stability with time in a conventional piezoelectric oscillator using an accumulation type MOS capacitance element is improved. A P-channel transistor type or an N-channel transistor type is used as a MOS capacitance element in a variable capacitance circuit used in a piezoelectric oscillator. A bias voltage is applied between P-type or N-type extraction electrodes formed in source and drain regions and an N-type extraction electrode provided in an N-well region or a P-type extraction electrode provided in a P-well region. Instability in the MOS capacitance element with time is thus eliminated.