On-chip light sensor
US5481118A · kind A · utility
69Cited by
14References
20Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Jan 26, 1995 |
| Grant date | Jan 2, 1996 |
| Priority date | — |
| Expiry date | Jan 26, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K17/785
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A brightness sensing circuit for providing a binary electrical signal for indicating whether incident light exceeds a certain brightness. The circuit's light detector is a photodiode, whose output is amplified by a first current mirror. The circuit has a reference current source, whose output is amplified by a second current mirror. Both currents are delivered to a common node, whose voltage level transitions from low to high when the amplified input current exceeds the amplified reference current. This node is connected to the gate input of a CMOS inverter, which provides a binary output.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.