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:
Mar. 26, 1996
Filed:
Nov. 18, 1994
Applicant:
Inventors:
Assignee:
Hitachi, Ltd., Tokyo, JP;
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H02H / ; G05F / ; H01L / ;
U.S. Cl.
CPC ...
257570 ; 257551 ; 257577 ; 361263 ; 3152 / ; 123651 ; 327110 ; 327575 ;
Abstract
A power transistor device is provided which has a function of clamping the collector voltage to a stable level for a wide range of temperature variations. In the power transistor device, a plurality of pn junctions are formed to fabricate Zener diodes in the polycrystalline silicon film in the form of rings. The ring configuration of the Zener diodes eliminates an end at the pn junction and prevents the junction surface from being exposed, making it possible to use as a stable Zener voltage the dielectric strength characteristic of the pn junction having a very small temperature coefficient.