Reducing the output filter of a Class-D amplifier
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چکیده
A properly designed Class-D output filter limits supply current, minimizes EMI and protects the loudspeaker from switching waveforms. However, it also significantly increases the total design cost. The current recommended second-order output filter for the TI TPA005D02 is 30% of the audio power amplifier (APA) solution cost. This application note details the second-order Butterworth filter and two reduced filtering techniques, each providing a different price/performance node. The first alternative to the Butterworth filter reduces the output filter by half and the second option completely eliminates the filter. The filters were tested using Texas Instruments TPA005D02 Class-D APA. Design decisions based on the measured results and conclusions are drawn to provide practical solutions for applications with different price/performance nodes.
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