Sinusoidal Pulse Width Modulation
The monostable multivibrator, with the modulating signal at the control voltage terminal, gives pulse width modulation according to the modulating signal. For this, the basic requirement is, pulse duration of mono-stable circuit should be far less than the time period of the modulating signal. The frequency of the Trigger input should be far higher than the modulating signal. This type of circuit is generally used in inverter design. Trigger input of about 20 KHz is used and the modulating signal will be sinusoidal at this power frequency. This is just a basic idea, but actual frequencies are obtained by lots of calculations to reduce harmonics and to produce the desired magnitude of voltage.
Sinusoidal Pulse Width Modulation