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:
Jan. 10, 1995
Filed:
Oct. 28, 1993
Bernard L Morris, Allentown, PA (US);
AT&T Corp., Murray Hill, NJ (US);
Abstract
An integrated circuit is disclosed comprising a first field effect transistor having a source connected to a first node and a gate connected to a second node, and a second field effect transistor for protecting the first transistor from voltages applied to the first node and greater than a predetermined nominal voltage. The second transistor includes a drain connected to the second node, a source connected to the first node, and a gate connected to a third node. A constant voltage source is coupled to the third node and supplies a gate voltage to the gate of the second transistor such that a drain-source path of the second transistor does not conduct while voltage applied to the first node is generally less than the gate voltage plus a threshold voltage of the second transistor. The constant voltage source comprises a third field effect transistor having a drain and a gate connected to the third node, and a source coupled to a first power supply voltage, such that the gate voltage is substantially equal to the first power supply voltage minus a threshold voltage of the third transistor.