The benefits of Dual-Band Pulse Width Modulation (DBPWM) are demonstrated for filter-less audio class-D amplifier implementations. DBPWM is evaluated in terms of energy efficiency (thermal loading) and reproduction fidelity for direct driving of loudspeaker units by DBPWM signals. Detailed physical models of low-frequency (woofer) and high-frequency (tweeter) loudspeakers are employed for simulation of the coupling between the DBPWM signal and the electro-mechanical and acoustic properties of loudspeaker systems in the broadband PWM spectral range. Derived frequency responses are used to estimate the reproduced sound signal of the loudspeaker. Equivalent impedance of the speaker's voice coil is used to estimate thermal loading by the DBPWM signal's out-of-band spectral energy, comparing standard filtered PWM implementations to the proposed method.
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