Patent Number: 7,088,140

Title: High speed IO buffer using auxiliary power supply

Abstract: Circuits, methods, and apparatus that provide output drivers that consume relatively little integrated circuit area and provide fast output switching. An exemplary embodiment provides an output driver including pull-up and pull-down devices, each device driven by a pre-driver stage. The pre-driver for the pull-down device is supplied from an auxiliary power supply, which has a higher voltage than the supply seen by the pull-up device. The pre-driver for the pull-down is biased by a voltage that tracks the higher of the auxiliary and output supplies. In some embodiments, the output driver may be part of an input/output cell. In that case, the well for the pull-up device is biased by a voltage that tracks the highest of the output supply and input received voltage, while the pull-up predriver circuit bias is the higher between the auxiliary and output supplies and the input received voltage.

Inventors: Nguyen; Khai (San Jose, CA), Sung; Chiakang (Milpitas, CA), Rangan; Gopi (Milpitas, CA), Chang; Tzung-Chin (San Jose, CA)

Assignee: Altera Corporation

International Classification: H03K 19/0175 (20060101)

Expiration Date: 8/08/02018