PSpice User Guide

PSpice User Guide

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PSpice User Guide Digital worst-case timing analysis October 2019 664 Product Version 17.4-2019 © 1999-2019 All Rights Reserved. to the unbounded accumulation of ambiguity in the feedback path. A simple example of this effect is shown in Figure 16-10. Figure 16-10 Cumulative ambiguity hazard example three. Due to the accumulation of ambiguity in the loop, the output signal will eventually become X, because the ambiguities of the rising and falling edges overlap. However, in the hardware implementation of this circuit, a continuous phase shift with respect to absolute time is what will actually occur (assuming normal deviations of the rise and fall delays from the nominal values). Note: If this signal were used to clock another circuit, it would become the reference and the effects of the phase shift could be ignored. You can do this by setting the NAND gate's model parameter, MNTYMXDLY=2 to utilize typical delay values for that one gate only (all other devices continue to operate in worst-case mode). OSC OSC

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