According to the invention, systems, apparatus and methods are disclosed
for providing bimodal voltage references for use in differential signaling
between components or devices. In an embodiment, a switchable power supply
is used to produce at least one of two or more supply voltages based on
the value of a selection signal received by the switchable power supply.
This selection signal is also used by at least one of the elements to
switch between a reference voltage produced by another device and a
reference voltage derived from the supply voltage. In certain embodiments,
the reference voltage derived from the power supply and the selection via
a multiplexing circuit is contained within one of the devices (e.g., a
chip), which provides certain design and cost advantages.