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:
Feb. 17, 1998
Filed:
Sep. 26, 1996
Shuji Shibuya, Kanagawa, JP;
Hisato Takeuchi, Kanagawa, JP;
Makoto Eguchi, Kanagawa, JP;
Takaharu Saeki, Kanagawa, JP;
Matsushita Electric Industrial Col., Ltd., Osaka, JP;
Abstract
In order to realize highly accurate temperature compensation of a crystal oscillation frequency, a current in proportion to the cube of a difference between an ambient temperature T.sub.a and a reference temperature T.sub.0 is generated. For this purpose, provided are a first series circuit of two diodes; a second series circuit of three diodes; a third series circuit of two diodes; a fourth series circuit of three diodes; a current source for allowing a constant current to flow into the first series circuit; a current source for allowing a constant current to flow from the third series circuit; a current source for allowing a current in proportion to T.sub.a -T.sub.0 to flow into the second series circuit when T.sub.a .gtoreq.T.sub.0 and allowing a current in proportion to .vertline.T.sub.a -T.sub.0 .vertline. to flow from the fourth series circuit when T.sub.a <T.sub.0 ; an NPN transistor and a PNP transistor whose collectors are connected with an output terminal; and two operational amplifiers for applying a voltage between the anode terminals of the first and second series circuits between the base and the emitter of the NPN transistor and for applying a voltage between the cathode terminals of the third and fourth series circuits between the base and the emitter of the PNP transistor, respectively.