Transmission line effects in Class D amplifiers — The peak control function as a design tool

Class D amplifiers find new applications in RFID systems, because of their high efficiency. Most textbooks describe the case of a load directly connected to the amplifier. However, in most RFID systems the usage of a transmission line is mandatory and this may introduce some novel effects, in the form of an infinite series of peaks in the system transfer functions. If not appropriately taken care of, these effects may lead to EMC issues. The purpose of the paper is to introduce the peak control function that allows the designer to keep the magnitude of the peaks and hence their influence on the system into well defined limits.