Exar Corporation

Saied Rafati

Bahram Fotouhi

Roubik Gregorian

Bahman Farzan

The separate high speed and full speed drivers used in a Universal Serial Bus 2.0 application can be combined into one driver which functions both as full speed/high speed driver and as a result provides output impedance for the full speed/high speed modes which is less process dependent.

Combined full speed and high speed driver

A protection circuit for a transmission gate having a PMOS transmission gate transistor and an NMOS transmission gate transistor coupled between a core circuit and an I/O pad. Biasing transistors are coupled to gates of the NMOS and PMOS transmission gate transistors to turn them on during normal operation. A protection circuit will turn off the NMOS and PMOS transmission gate transistors when the voltage at the pad exceeds the supply voltage by more than a threshold amount. This protection circuit includes a first protection transistor coupled between the gates of the biasing transistors and the pad to turn the biasing transistors off when the voltage on the pad exceeds the supply voltage by more than the threshold amount.

I/O pad overvoltage protection circuitry

An operational amplifier that exhibits a relatively constant gain over process and temperature variations. The operational amplifier according to the present invention is designed such that its gain does not depend on process sensitive parameters such as mobility of field effect transistors.

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Saratoga, CA, United States of America

Saied Rafati