A variable-voltage bidirectional I/O pad for digital GaAs applications

A bidirectional I/O pad for digital GaAs applications has been designed, fabricated, and tested using Vitesse Semiconductor process technology. The I/O pad is designed to operate at frequencies up to 500 MHz and at GTL, ECL, or Rambus voltage levels. The I/O pads can be calibrated to these voltage levels either manually using external signals or internally using on-chip digital calibration logic.