Comparator for input voltages higher than supply voltage
US7315187B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 21, 2005 |
| Grant date | Jan 1, 2008 |
| Priority date | — |
| Expiry date | Jan 17, 2026 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K5/2472
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A comparator has first and second current paths, each passing from an input through a transistor, through a current source to ground, the second current path also having a reference voltage drop element coupled in series with the second input. The gates of the transistors are coupled to form a current mirror. The reference voltage drop element enables higher voltages to be input and compared to higher thresholds above an internal supply voltage level without the need for dividing resistors to reduce the input voltage. Avoiding such resistors means the power dissipation and the silicon area used can be kept lower. ESD vulnerability is reduced since the inputs are not coupled to gates of MOS transistors. Overvoltage protection across the source and gate of the second transistor can be added.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.