BICMOS electrostatic discharge protection circuit
US5521789A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 15, 1994 |
| Grant date | May 28, 1996 |
| Priority date | — |
| Expiry date | Mar 15, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H9/046
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An enhanced bipolar-transistor apparatus for protecting electronic devices from electrostatic discharge damage. The apparatus is built around a bipolar transistor coupled between a power rail and the circuit to be protected. The protection is based on the high-current-capacity path through the bipolar transistor which is opened up either by collector-to-emitter punch-through in the bipolar transistor or by the bipolar transistor going into normal conduction upon being turned on by a switch coupled to the base of the bipolar transistor. In the preferred embodiment the switch is a MOS transistor that is designed to undergo source-to-drain breakdown at a fixed threshold voltage, whereupon it activates the bipolar transistor which in turn discharges the overvoltage. In this way the advantages of the high-current-capacity bipolar transistor are obtained without the concern that fabrication vagaries will prevent the bipolar transistor from providing needed protection, such as is the situation where the punch-through phenomenon alone is relied on.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.