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:
May. 22, 2001
Filed:
Nov. 02, 1998
Michael P. Daly, Newtownmountkennedy, IE;
Denis Ellis, Patrickswell, IE;
Keith A. Moloney, Crecora, IE;
Liam J. White, Patrickswell, IE;
Brian A. Moane, Ballykeeffe, IE;
Kieran Heffernan, Patrickswell, IE;
Denis Joseph Doyle, Limerick, IE;
Michael G. Tuthill, Raheen Cross, IE;
David John Clarke, Patrickswell, IE;
Analog Devices, Inc., Norwood, MA (US);
Abstract
An input protection device is provided for protecting a circuit structure which is coupled to a first node, the device comprising a first lightly-doped region of P-type material with a lightly doped well of N-type material formed in it. Two regions of heavily doped N-type and P-type material, which are electrically connected to the first node, are formed in the well of N-type material. A third heavily doped region of N type material is formed in the first lightly-doped region of P-type material and is electrically connected to a reference node. In a first aspect of this invention, the third heavily doped region of N type material is formed in a second well of N-type material, which in turn is formed in the first lightly-doped region of P-type material. In this first aspect of the invention a further region of heavily doped P-type material is formed in the second well of N-type material, this further region of heavily doped P-type material being electrically connected to the reference node. In a second aspect to the invention, a further region of heavily doped P-type material is formed in the first lightly-doped region of P-type material. In a third aspect to the invention, the third heavily doped region of N type material is formed in a second well of N-type material, which in turn is formed in the first lightly-doped region of P-type material. In this third aspect of the invention a further region of heavily doped P-type material is formed in the second well of N-type material, this further region of heavily doped P-type material being electrically connected to the reference node, with a further region of heavily doped P-type material formed in the first lightly-doped region of P-type material. Accordingly, an input protection device for protecting pins of an integrated circuit is described having both bipolar and unipolar characteristics. The input protection device may be constructed as a discrete device or as part of an integrated circuit and provides for breakdown voltages in excess of a supply voltage to an integrated circuit. The characteristics, in particular the breakdown voltage, of the input protection device are alterable by adjusting its layout, in contrast to a known method of altering such characteristics by altering doping levels.