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:
Apr. 10, 2001
Filed:
Jan. 08, 1998
Eiichi Hasegawa, Tokyo, JP;
Haruhiko Otsuka, Tokyo, JP;
Nippon Precision Circuits Inc., Tokyo, JP;
Abstract
A crystal oscillator circuit includes a CMOS invertor having an input terminal and an output terminal, a crystal resonator connected between the input terminal and the output terminal respectively at a first connection node and a second connection node, and a feedback resistor connected between the input terminal and the output terminal of the CMOS invertor. A first capacitor is provided between the first connection node and a power source terminal at a predetermined potential and a second capacitor is provided between the second connection node and a power source terminal at the predetermined potential. At least one resistor is disposed in series with at least one of the first capacitor and the second capacitor and has a resistance so as to limit a crystal current in the crystal resonator while maintaining negative resistance for stable oscillation. In an embodiment, a resistor is provided in series with each capacitor. Furthermore, an embodiment of the invention includes an integrated circuit permitting the above circuit structure with the crystal resonator and first and second capacitors accommodated external of the integrated circuit. Alternatively, the first and second capacitors may be accommodated on the integrated circuit.