Over the years, there have been a large number of papers published related to switching power amplifiers. However, to the best of the author's knowledge, there has been little information published about the demodulation technique required for switching amplifiers. While the purpose of the demodulating filter is to strip the carrier frequency from the information signal, improper design and selection of passive components will seriously affect the filter's attenuating performance. This paper will explain the basics of a demodulating filter; showing attenuation responses of different structures and number of stages. The selection of component values and types, as well as their affects on cost and attenuation performance, will also be discussed. Finally, this work will analyze simulation responses of LC filters modeled with parasitics that can be compared to real LC filters.
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