Systematic design of output filters for audio class-D amplifiers via Simplified Real Frequency Technique

[摘要] In this paper a new filter design concept is proposed and implemented whichtakes into account the complex loudspeaker impedance. By means of techniquesof broadband matching, that has been successfully applied in radiotechnology, we are able to optimize the reconstruction filter to achieve anoverall linear frequency response. Here, a passive filter network is insertedbetween source and load that matches the complex load impedance to thecomplex source impedance within a desired frequency range. The design andcalculation of the filter is usually done using numerical approximationmethods which are known as Real Frequency Techniques (RFT). A first approachto systematic design of reconstruction filters for class-D amplifiers isproposed, using the Simplified Real Frequency Technique (SRFT). Somefundamental considerations are introduced as well as the benefits andchallenges of impedance matching between class-D amplifiers and loudspeakers.Current simulation data using MATLAB is presented and supports some firstconclusions.

[学科分类] 电子、光学、磁材料