Analysis of double-T filter used for PWM circuit to D/A converter

In practice applications, high-precision analog output is often required for complex process control, so the PWM (Pulse Width Modulation) output should be converted to smooth direct current output. A simple, practical and high-precision conversion and analysis method is presented in this paper. After transforming the PWM waveform with Fourier Transform Method, the digital-analog converter signal, which is demodulated through PWM, can be modulated with the low-pass filter. Thus the conversion from PWM to DAC (Digital to Analog Converter) can be realized. For the typical double-T filter circuit, based on the concept of closed-loop dominant pole in classical control theory, the order of the transfer function expression is reduced. The mathematical analysis to direct current component of PWM signal obtained through Double-T filter circuit is verified by simulation. Finally, the conversion rapidity and accuracy of this method for DAC is discussed.