Duty Cycle and Pulse Width: Definition, Formula, and Key Differences

Duty Cycle and Pulse Width are two important terms used to describe the characteristics of periodic signals, especially in electronics and communication systems. The Pulse Width refers to the duration of time a signal stays in its active or “high” state during each cycle, usually measured in microseconds or milliseconds. The Duty Cycle is the percentage of one complete cycle during which the signal remains active. Both these parameters play a crucial role in controlling devices like motors, LEDs, and communication signals. Understanding their difference and calculation is essential for accurate signal control and system performance.

Duty Cycle

When you look at the duty cycle, you’re seeing it defined as the ratio of on-time to the total time (on-time plus off-time). The rise and fall transitions dictate the lengths of on-time and off-time. But in real situations, these transitions aren’t identical, so the duty cycle can fluctuate, leading to less accurate calculations. For example, in the image, the input starts with a 50%-50% balance between rise and fall transitions. After passing through certain components, though, you’ll notice around an 8% variation in both rise and fall times.

The Pulse Width

The pulse width, on the other hand, is affected by variations in the rise and fall transitions compared to the input transitions. Consequently, the threshold (50%) deteriorates. This results in a decrease in the pulse width. Reduced pulse width can lead to the loss of data that was meant to be captured at a specific time.