Patent ID: 7417459

Claim:
An integrated circuit comprising: an offset reference circuit block, disposed in a die, adapted to receive a first reference voltage from an external voltage source, and to output a second reference voltage based at least in part on the first reference voltage, the offset reference circuit blocking including: an operational amplifier having a first input terminal coupled to a die pad to receive the first reference voltage, a second input terminal, a first output terminal, a feedback loop adapted to couple the first output terminal to the second input terminal, the first output terminal adapted to manifest a third reference voltage that is negatively offset from the first reference voltage, the feedback loop including a first resistive device adapted to provide a first resistance that is variable, a first segment adapted to couple a first voltage source to the second input terminal of the operational amplifier, the first segment having a second resistive device adapted to provided a second resistance in series with a third resistive device adapted to provide a third resistance that is variable, a second output terminal disposed between the second resistive device and the third resistive device and adapted to manifest a forth reference voltage that is positively offset from the first reference voltage, and a multiplexer coupled to the die pad, the first output terminal and the second output terminal and adapted to generate the second reference voltage by selectively outputting the first reference voltage, the third reference voltage, or the fourth reference voltage manifested on the die pad, the first output terminal, and the second output terminal, respectively; and an input/output buffer, disposed in the die, and coupled to the offset reference circuit block, the input/output buffer adapted to receive the second reference voltage and operate to buffer input data from an external data source or buffer output data for an external data sink, based at least in part on the second reference voltage, each of the external data source and the external data sink being adapted to receive and operate based on the first reference voltage.