A low THD analog Class D amplifier based on self-oscillating modulation with complete feedback network

We propose a novel analog Class D Amplifier (CDA) based on self-oscillating modulation where the input of the feedback network is taken at the output of the lowpass LC filter (complete feedback') as opposed to the prevalent (Pulse Width Modulation CDA) approach where the feedback input is taken at the output of the output stage of the CDA ('incomplete feedback'). The complete feedback approach substantially suppresses the non-linearity of the inductor of the Lowpass filter as this filter now constitutes part of the feedback loop. The proposed approach is highly hardware efficient over reported prevalent complete feedback CDAs. When the proposed complete feedback CDA is compared against the prevalent incomplete feedback approach, the proposed CDA exhibited highly suppressed THD (similar to 40dB relative suppression in most cases). The THD of the proposed CDA is <= 0.012% for the complete modulation index range and pertinent input signal range. Means to further reduce the THD is also suggested.