Patent ID: 6859066

Claim:
Interface circuitry for a programmable semiconductor device, comprising: a plurality of voltage rails; a plurality of input buffers; a plurality of input pads corresponding to the plurality of input buffers, each input buffer operable to receive a single-ended signal from the corresponding input pad; a plurality of demultiplexers corresponding to the plurality of input buffers and to the plurality of input pads, wherein each demultiplexer is operable to receive a reference voltage from the corresponding input pad and selectively couple the reference voltage to one of the voltage rails; a plurality of low pass filters corresponding to the plurality of demultiplexers and to the plurality of input pads, each low pass filter being operable to inhibit noise from the corresponding input pad from coupling through the corresponding demultiplexer to the voltage rails; and a plurality of multiplexers corresponding to the plurality of input buffers, wherein each multiplexer is operable to select one of the voltage rails and couple the selected voltage rail to the corresponding input buffer.