PPT Slide
3 – Combinational Logic Implementation
Time behavior of combinational networks
Waveforms
- visualization of values carried on signal wires over time
- useful in explaining sequences of events (changes in value)
Simulation tools are used to create these waveforms
- input to the simulator includes gates and their connections
- input stimulus, that is, input signal waveforms
Some terms
- gate delay — time for change at input to cause change at output
- min delay – typical/nominal delay – max delay
- careful designers design for the worst case
- rise time — time for output to transition from low to high voltage
- fall time — time for output to transition from high to low voltage
- pulse width — time that an output stays high or stays low between changes