High voltage current source circuit and method
US4659979A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 27, 1985 |
| Grant date | Apr 21, 1987 |
| Priority date | — |
| Expiry date | Nov 27, 2005 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F2203/45144
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A high voltage constant current source circuit includes first transistor biased as a constant current source and a second transistor connected in series with the first transistor. The second transistor has a punch-through voltage that is substantially less than any breakdown voltage of the second transistor. The emitter of the second transistor is connected to the collector of the first transistor. The collector of the second transistor supplies the constant current, provides an increased high output impedance, and allows low voltage operation if the collector-to-emitter voltage of the second transistor is less than its punch-through voltage. If its punch-through voltage is exceeded, that punch-through voltage adds to the collector-to-emitter breakdown voltage of the first transistor, allowing high voltage operation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.