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:
Oct. 17, 1995
Naoto Okabe, Aichi, JP;
Naohito Kato, Aichi, JP;
Nippondenso Co., Ltd, Kariya-city, JP;
Abstract
The insulated gate bipolar transistor (IGBT) integrates the anti-excess voltage protection function and a drain voltage fixing function. When a voltage is applied across the drain electrode and the source electrode of the IGBT, a depletion zone propagates from a p-n junction between a p base layer and a n.sup.- drain layer toward inside of the n.sup.- drain layer. A critical electric field is also established, causing generation of a great number of electron-hole pairs due to impact ionization of carriers in or near the n.sup.- drain layer. Conduction exist between the drain electrode and the source electrode, at an applied voltage lower than a drain-source voltage at which the depletion region reaches a p.sup.+ drain layer through the n.sup.- drain layer, the applied voltage being equal to or lower than a critical voltage that causes generation of a great number of electron-hole pairs due to impact ionization of carriers in or near the n.sup.- drain layer below a p-n junction between a p-type guard ring and the n.sup.- drain layer.