Low voltage, high precision current source
US4647841A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 21, 1985 |
| Grant date | Mar 3, 1987 |
| Priority date | — |
| Expiry date | Oct 21, 2005 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG05F3/267
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A precision current mirror circuit includes first and second transistors the bases of which are coupled together and whose emitters are coupled to ground. The collector of the first transistor is connected to a reference current source for sinking a reference current therefrom while the collector of the second transistor is connected to an output of the current error for sinking a current at the output that substantially mirrors the reference current. A differential amplifier is provided having its non-inverting and inverting inputs coupled to the collectors of the first and second transistors respectively and its output connected to the bases of the two transistors such that the voltage that is established at the output of the current mirror is forced onto the collector of the first transistor. With the two transistors being matched the respective collector-base voltages therefore track which eliminates "Early" voltage errors as well as affects of the lower output impedances of the two transistors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.