Geodesic Theory of Zero-Voltage-Switching RF Power Inverters for Constant-Voltage or -Current Output Operation

This paper presents a novel design theory for radio frequency (RF) inverters. We project the zero-voltage-switching (ZVS) and zero-voltage-derivative-switching (ZVDS) load impedances on the Smith chart, and find out that their loci exhibit geodesic arcs. We show that any complex impedance can be transformed by a lossless reciprocal network from one geodesic to another. Exploiting this geometric theorem, we establish a design theory of geodesic-to-geodesic (G2G) networks, which employs three LC elements. With the G2G network, RF-switching inverters can achieve ZVS operations over the full load resistance range. The G2G inverter maintains its output voltage or current at a constant amplitude. The design theory is verified via circuit simulations. The presented theory is quite elegant as it is based on a graphical approach.