Exar Corporation

Bahman Farzan

Bahram Fotouhi

Hung Pham Le

Saied Rafati

An electrostatic discharge protection device is disposed between true-complement input pins of a differential signal pair and a ground node. A common node couples the three diode stacks together. A first and a second diode stack each connect to one of the differential signal pair input pins. The third diode stack couples to the ground node. Each of the diode stacks is fabricated by a pair of high concentration p-type contact dopant regions within a low concentration n-well region. Each of the p-type contact dopant regions is configured to form back-to-back diodes connected in series with cathodes in common. In protecting common mode receivers, current from an ESD event is channeled to ground rather than to the complementary receiver node. The diode stacks are capable of withstanding a 15 kV incident and save up to 25% in area compared to a fully parallel configuration for differential signal pairs.

Low-voltage CMOS space-efficient 15 KV ESD protection for common-mode high-voltage receivers

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

Method and circuitry for differential output driver with monotonic output transitions. The switching sequence for the output driver transistors of the differential driver changes depending on the direction of the input signal transition. When the input makes a binary transition from high to low, each one of the output driver transistors is switched on or off at a different time based on a first predetermined sequence. When the input makes the opposite binary transition (low to high), each one of the output driver transistors is switched on or off at a different time based on a second predetermined sequence that is different than the first sequence. The predetermined sequences are designed to eliminate any possibility of a glitch or non-monotonic behavior at the output terminals.

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Mountain View, CA, United States of America

Bahman Farzan