What is the duty cycle of the output waveform in Fig. 36-13b?
What is the duty cycle of the output waveform in Fig. 36-13b?
Recall that the duty cycle is defined as the pulse width divided by the period. Duty cycle equals the conduction angle divided by 360°.
In Fig. 36-13b, the sine wave has a peak value of 10 V. Therefore, the input voltage is given by
v_{in} = 10 \sin \thetaThe rectangular output switches states when the input voltage crosses +5 V. At this point, the foregoing equation becomes
5 = 10 \sin \thetaNow, we can solve for the angle \theta where switching occurs:
\sin \theta = 0.5or
\theta = arcsin 0.5= 30° and 150°
The first solution, \theta = 30°, is where the output switches from low to high. The second solution, \theta = 150°, is where the output switches from high to low. The duty cycle is
D=\frac{conduction angle}{360°}=\frac{150°-30°}{360°}= 0.333The duty cycle in Fig. 36-13b can be expressed as 33.3%.