Advanced Micro Devices, Inc.
Gate-source voltage generation for pull-up and pull-down devices in I/O designs

Abstract:

Driver and pre-driver circuitry operate in an integrated circuit with two supply voltages. In one form, a reference voltage generation circuit is operable to respond to varying voltage supply conditions in which a driver may be subject to over voltage effects by generating a reference voltage based the first supply voltage when the second supply voltage is not available, and based on the second supply voltage when the first supply voltage is not available. A first drive signal generation circuit drives a pull-up transistor gate based on a data signal, varying the gate voltage between the second supply voltage and the reference voltage. A second drive signal generation circuit drives a pull-down transistor gate with a signal varying between the second supply voltage minus the reference voltage, and zero volts. In one form, certain gate-source voltages in the driver are maintained to be equal.