A Pulse-Width Modulation (PWM) demodulator is a device or circuit that is used to recover the original analog signal from a Pulse-Width Modulated signal. PWM is a common method of encoding analog information into a digital signal, where the information is represented by the width of the pulses in the signal.
In a PWM signal, the duty cycle (ratio of pulse width to the period) varies in proportion to the amplitude of the analog signal. A higher duty cycle represents a higher amplitude, while a lower duty cycle represents a lower amplitude.
The PWM demodulator's primary purpose is to convert the PWM signal back into its original analog form, which can be understood by electronic devices or human beings. The demodulation process involves the following steps:
Sampling: The PWM signal is sampled at a regular interval. This is typically achieved using a clock or a timer.
Pulse Width Measurement: During each sampling period, the width of the PWM pulse is measured. This is done by determining the time between the rising edge and falling edge of the pulse.
Duty Cycle Calculation: The duty cycle of each pulse is calculated by dividing the pulse width by the sampling period.
Reconstruction: The duty cycle information is then used to reconstruct the original analog signal. This can be done using various methods, such as low-pass filtering or interpolation.
Output: The reconstructed analog signal is the demodulated output, which represents the original information encoded in the PWM signal.
PWM demodulation is commonly used in various applications, including motor control, audio signal processing, communication systems, and power electronics, where PWM signals are used for efficient data transmission and control.