Methods of using "noise cores" in a PLD design. "Noise cores" are pre-developed
blocks of logic included in a PLD design for the purpose of creating noise in other
circuits also implemented in the PLD. By gradually increasing the level of noise
created by the noise core, the noise sensitivity of the user circuit can be determined.
Also, by ensuring that the user circuit functions properly when combined with the
noise core, a designer can have confidence that unmodified portions of the user
circuit will still function properly when the user circuit is modified. In some
embodiments, once the user circuit has been qualified with the noise core operational,
the noise core is disabled prior to including the PLD design in a system. Because
the user circuit is proven to withstand a certain level of noise, future additions
to the design do not necessarily require re-qualification of the user circuit.
