On/off reference voltage switch for multiple I/O standards
US6911860B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 9, 2001 |
| Grant date | Jun 28, 2005 |
| Priority date | — |
| Expiry date | Nov 9, 2021 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K17/063
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A switch circuit selectively provides a reference voltage, needed in some I/O standards, to a logic device. The circuit receives a dedicated power supply that is different from the device's I/O supply. It may also include a level shifting circuit for converting a master control signal having a logic level determined by a first supply to a first control signal having a logic level determined by the dedicated supply. The switch circuit also includes a transmission switch that passes the reference voltage to an output in response to at least the first control signal. The transmission switch may be a CMOS transmission gate with at least one NMOS transistor controlled by the first control signal in parallel with at least one PMOS transistor controlled by a second control signal, complementary to the first. The second control signal may be generated by another level shifting circuit and have a logic level determined by the I/O supply.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.