The Peak Control Function and its Applications to Transmission Line Effects in Class D Amplifiers

Abstract

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 frequency response functions. If not appropriately taken care of, these effects may lead to electromagnetic compatibility problems. The purpose of the paper is to develop the theory of the peak control function, which is conceived as a tool that allows the designer to keep the magnitude of the peaks, and hence their influence on the system, into well defined limits.

Keywords

• radiofrequency identification
• switching circuits
• power amplifiers
• transmission lines
• frequency response