Variable output-type constant current source circuit
US7057448B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 1, 2004 |
| Grant date | Jun 6, 2006 |
| Priority date | — |
| Expiry date | Jun 10, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG05F3/262
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
Disclosed is a variable output-type constant current source circuit capable of varying its output current in a stepwise manner without the complication in circuit configuration and the increase in size of a semiconductor circuit board for incorporating the circuit therein. The constant current source circuit comprises a first self-biasing type constant current circuit 3a configured such that transistors M1, M2 are operable to cooperatively supply a given voltage across a resistor RS to generate a stabilized current IR1. In order to vary the output current, the constant current source circuit includes a switching circuit 5 (transistor M5) connected in series to a series circuit connecting in series the transistor M1 and the resistor RS, and a second constant current circuit 4 connected in parallel to a series circuit connecting in series the transistor M1, the resistor RS and the transistor M5. The second constant current circuit 4 is also configured to serve as an activation circuit for the first constant current circuit 3a.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.