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pulse width modulation (PWM)

Pulse width modulation (PWM) modulates the pulse width of a square-wave signal. The pulse width modulation method, which is used in controllers among other things, works with a constant pulse frequency and a constant pulse amplitude, only the pulse width is variable. Because the pulse frequency is constant, but the pulse width changes, the duty cycle changes.

Depending on the technical implementation, pulse width modulation works with a modulation signal or according to the comparator principle with edge control. In this principle, the linear amplitude rise of a sawtooth signal is compared with a variable comparison voltage and, if the voltage is equal, the output level of the comparator is switched over. If the reference voltage is changed, the switching time and thus the pulse width also changes.

Pulse width modulated with a digital signal

Pulse width modulated with a digital signal

Pulse width modulation is also known as pulse width or pulse duration modulation and is used in D/A converters, switching power supplies, telemetry, power electronics for controlling electric motors and dimmers, and also in optical transmitters, among other applications.

Pulse width modulation with an analog signal

Pulse width modulation with an analog signal

In these, for example, a wide light pulse represents a logic "1", and a narrow light pulse represents a logic "0". The light level is the same for both logical states.

In D/A conversion, the pulse width and thus the duty cycle is determined by the digital value. The average value of the duty cycle corresponds to the analog output voltage.

Informations:
Englisch: pulse width modulation - PWM
Updated at: 08.06.2015
#Words: 241
Links: modulation, pulse width (PW), signal, method, constant
Translations: DE
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