Photodiode amplifier circuit with improved sensitivity to high efficiency illumination
US5498865A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 16, 1994 |
| Grant date | Mar 12, 1996 |
| Priority date | — |
| Expiry date | Dec 16, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01J1/44
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A photodiode amplifier includes an input stage having a first pair of transistors connected as a differential pair to have a low input impedance and a current source connected into the input stage to bias the pair of transistors. A photodiode is connected into the input stage across the transistors so as to provide differential effect to current flowing through the transistors. By means of such connection, the photodiode is presented with low input impedance, its time constant is accordingly lowered, and the system response of the photodiode amplifier is extended into higher frequencies. The photodiode amplifier is of particular use in an illuminant discriminator capable of distinguishing a range of separate illuminants, including high efficiency fluorescent lighting within the passband of the photodiode amplifier.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.