In PWM, the time period of the square wave is kept constant and the time for which the signal remains high is varied or modulated. The duty cycle and average DC value of the signal can be varied. PWM provides a powerful method for controlling analog circuits with the help of an output from a digital system. A few applications of PWM technique include:

• Telecommunication—Data corresponding to particular pulse widths is encoded at one end and decoded at the other end.
• Voltage regulation—The output voltage in a voltage regulator system can be controlled to a desired level by varying the duty cycle.
• Power delivery—You can vary the average power delivered, which is a function of the modulated duty cycle.
• Audio Effects and Amplification—Used in sound synthesis.

You can visually observe PWM with intensity variation in LEDs, which are known for their fast switching speeds. Intensity variation in the LED is an outcome of the variation in average DC voltage and the current through the LED due to PWM.