Current measuring circuit with means for nullifying the effects of current source and lead resistance
US5008523A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 26, 1989 |
| Grant date | Apr 16, 1991 |
| Priority date | — |
| Expiry date | Sep 26, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R19/0023
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Current derived from an indium arsenide current generating photodetector is determined accurately, despite the presence of a variable resistance between terminals of the photodetector and the photodetector having leads with appreciable resistance connected to the detector terminals. Two leads are connected to each detector terminal. The two leads connected to one of the detector terminals are respectively connected to an inverting input terminal of an operational amplifier and to one terminal of a feedback resistor of the amplifier; the other terminal of the feedback resistor is connected to the amplifier output terminal. The two leads connected to the other terminal of the photodetector are respectively connected to the operational amplifier non-inverting input terminal and to ground. The operational amplifier derives an output voltage that accurately represents the output current of the photodetector, independently of the photodetector resistance and the lead wire resistance.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.