Circuit for the protection of IGFETs from overvoltage
US4580063A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 1, 1982 |
| Grant date | Apr 1, 1986 |
| Priority date | — |
| Expiry date | Dec 1, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K19/00315
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A pair of IGFETs connected in cascade across a d-c power supply form a source/drain junction constituting the output terminal of a self-biasing amplifier to which binary-coded bipolar signals are transmitted by way of a voltage divider effectively inserted between an input terminal and the afore-mentioned junction, a tap of that voltage divider being connected to the gate of a first of these IGFETs whose source is tied to one of the two supply terminals; the drain and the gate of the second IGFET are tied to the opposite supply terminal. A protective diode lies between the input terminal and the supply terminal connected to the source of the first IGFET so as to be reverse-biased by the voltage divider in a quiescent state and to break down in the presence of an abnormally high input voltage of a given polarity (positive in the specific instance described). An ancillary IGFET connected between the input terminal and the opposite supply terminal has its gate biased at a potential so chosen that this IGFET conducts in the presence of an input voltage of the other (negative) polarity approaching the forward-conduction threshold of the protective diode so as to prevent that threshold f…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.