Hybrid controller for mid-power audio application

What is it about?

Class-D amplifiers have much higher energy efficiency when amplifying audio signals, in sharp contrast with conventional amplifiers but have poorer linearity. In this paper we have suggested a new scheme which shows great improvement in input-output linearity. For this we have nested a non-linear voltage control loop within an outer linear current regulation loop. Through a structured design approach, we have shown impressive flatness of the audio gain and reduction in phase lag across the entire audio spectrum.

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Why is it important?

We have shown the experimental steps required for modeling the loudspeaker, which is a key component in the audio playback chain. This is important since dynamic properties of the speaker structure differs widely between manufacturers and there is hardly any standardized behaviour. Subsequently we have laid down clear analytical steps to design the inner loop and, especially, the outer loop controller. The procedure is general enough and can be easily tailored for any other speaker with completely different dynamic behaviour to achieve similar levels of input-output linearity as has been schieved in this paper.

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