The Inherent Flaw of All Waveform Generators

By: Chris Bake

What Is a Duty Cycle?

Duty cycle is an important concept in electronics and refers to the ratio of the duration of a signal's active state to the total period of the signal. It is often expressed as a percentage, and it can be used to control the amount of power delivered to a device. Duty cycle is an essential parameter in many electronic devices, including pulse width modulation (PWM) systems, where it determines the average power delivered to the load.

The duty cycle of a signal is determined by the width of the pulse or the duration of time the signal is active, relative to the total period of the signal. For example, if a signal has a period of 1 second and is active for 0.5 seconds, its duty cycle would be 50%. A higher duty cycle indicates that the signal is active for a longer period of time relative to the total period, and vice versa for a lower duty cycle.

When the signal is high, we call this "on time". To describe the amount of "on time" , we use the concept of duty cycle. Duty cycle is measured in percentage. The percentage duty cycle specifically describes the percentage of time a digital signal is on over an interval or period of time. This period is the inverse of the frequency of the waveform.

If a digital signal spends half of the time on and the other half off, we would say the digital signal has a duty cycle of 50% and resembles an ideal square wave. If the percentage is higher than 50%, the digital signal spends more time in the high state than the low state and vice versa if the duty cycle is less than 50%. Here is a graph that illustrates these three scenarios:

50%, 75%, and 25% Duty Cycle Examples

100% duty cycle would be the same as setting the voltage to 5 Volts (high). 0% duty cycle would be the same as grounding the signal.

Regardless of the method of Duty control, the same behavior is presented.

The Inherent Problem

Let's say that you wanted to create a certain gated pulse waveform.

The Battle Of Clocks

The Adjustment Problem

Independent Width vs Spacing Control

In