Rise time measures how fast a digital edge or analog pulse transitions, typically calculated between the 10% and 90% voltage levels of the step. Fast rise times are necessary for high-speed digital logic but introduce high-frequency harmonics that cause ringing, crosstalk, and EMI. Engineers use oscilloscopes with sufficient bandwidth to accurately capture these fleeting transitions without artificially smoothing them out.
The rise time on this clock edge is too slow, which is why the flip-flop is occasionally double-clocking.
A common rule of thumb is that the required oscilloscope bandwidth to accurately measure a signal is 0.35 divided by the signal's rise time.
Related terms
Fall time
The duration required for a digital signal to transition from a high state to a low state.
Edge-triggered
A digital input that responds only to the transition of a clock signal.
Clock skew
The time difference between a clock signal arriving at different parts of a circuit.
Propagation delay
The time it takes for a logic signal to travel through a gate and change its output state.