Variable voltage cmos off-chip driver and receiver circuits

Abstract

A structure is described having a plurality of electronic devices with the same or different internal CMOS voltages; an interconnection between two or more of the electronic devices; driver and receiver circuits which provide selectable input/output voltage levels for interfacing with several generations of CMOS technology, thus allowing chips fabricated in such technologies to communicate using a signal voltage range most suitable for each chip; Circuitry for selecting or adjusting the type of receiver circuit used, thus allowing either the use of a differential comparator circuit with an externally supplied reference voltage, or alternatively, the use of an inverter style receiver with an adjustable threshold, the selection being accomplished by setting the external reference to a predetermined voltage; Circuitry for selecting or adjusting the switching threshold of the inverter receiver circuit, which enables the threshold to be set appropriately for a given input signal voltage range.