Circuit with hot electron protection and method
US5952875A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 9, 1997 |
| Grant date | Sep 14, 1999 |
| Priority date | — |
| Expiry date | Sep 9, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K17/0822
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An I/O circuit whose output receives a voltage V.sub.PAD which is temporarily higher than a critical voltage V.sub.DS MAX >V.sub.DS 1 across drain and source of a conducting first N-FET (110, N1) acting as a pull-down device. The first N-FET is protected against hotelectron induced degradation by a serially coupled second N-FET (130, N3). A variable drain-source voltage V.sub.DS 3 is added to V.sub.DS 1. A comparator (150) compares the received voltage V.sub.PAD to a supply voltage V.sub.CC and pulls a gate (G) of the second N-FET (N3) to V.sub.PAD or to V.sub.CC. The conductivity of the second N-FET (N3) is thereby changed so that VPAD is distributed among V.sub.DS 1 and V.sub.DS 2. The comparator (150) conveniently comprises two P-FETs (P1, P2, 160, 170).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.