Digital-to-analogue conversion using pulse width modulation
Pulse width modulation (PWM) has found application in various situations where efficient delivery of high power is required. In this paper its use in the conversion of signals from digital to analogue representations is addressed, i.e. as a digital-to-analogue converter (DAC), and it is shown that there are many advantages in using PWM over conventional DAC methods and that high resolution and accuracy can be achieved. One advantage is that, provided a suitable output stage can be provided, a complete, high-power, high-resolution digital-to-analogue power converter can be constructed. Because this work was motivated by the author's interest in digital audio, such a device has come to be known as a digital (power) amplifier. The article describes PWM, particularly in its digital forms, and shows how to make it practical for use as a DAC. This involves various digital signal processing stages prior to the final modulator. Results are presented from simulations and from demonstrator hardware.
