Comparison of Simple Self-Oscillating PWM Modulators

Switch-mode power amplifiers has become the conventional choice for audio applications due to their superior efficiency and excellent audio performance. These amplifiers rely on high frequency modulation of the audio input. Conventional modulators use a fixed high frequency for modulation. Self-oscillating modulators do not have a fixed modulation frequency and can provide good audio performance with very simple circuitry. This paper proposes a new type of self-oscillating modulator. The proposed modulator is compared to an already existing modulator of similar type and their performances are compared both theoretically and experimentally. The result show that the proposed modulator provides a higher degree of linearity resulting in around 2 % lower Total Harmonic Distortion (THD).