Radio-Frequency Inverters With Transmission-Line Input Networks

Abstract

A soft-switching inverter topology (the Class 8) is presented which draws dc source current through a transmission line or a lumped-network approximation of a distributed line. By aligning the inverter switching frequency just below the line's 4-wave resonance, the Class 8 topology enforces odd-and even-harmonic content in its drain voltage and input current, respectively. The symmetrizing action of the transmission-line dynamics results in natural square-wave operation of the switch, reducing the inverter stresses (relative to a Class E) for a given power throughput. The inverter waveforms and normalized power-output capability are analyzed in simple terms, and supported by measurements of an inverter built around a length of distributed line, and an inverter incorporating a lumpedladder network. The latter implementation is constructed with air-core magnetics and inter-layer capacitances that are integrated into the thickness of a printed-circuit board. A comparison with a Class E inverter of similar size and ratings demonstrates the small passive-component values and manufacturing advantages afforded by the Class 8 topology.

Evolution of Very High Frequency Power Supplies

“…1: Schematic of a self-oscillating VHF converter [24] with LED load. [26] or the input inductor [11], [27] with a transmission line. The resulting waveforms of this circuit have been reported in e.g.…”

“…Simultaneously VHF converters provide a major opportunity to overcome those. Among the challenges are core losses, skin and proximity effect [27], [49]- [54]. For driving further miniaturization of VHF power supplies an obvious next step is to integrate the whole converter in a package (Power Supply in Package (PSiP)) or even on a single chip (Power Supply on Chip (PwrSoC)).…”

Topologies and Control Strategies of Very High Frequency Converters: A Survey

“…In the present researches, most of the VHF circuits are based on the single switch structure to avoid floating drive. Combining with different structures of VHF power amplifiers, Class E topology [50], [51] and Class Φ 2 topology [52]- [55] are used to constitute the inverter and rectifier stage. The following sections will introduce these three parts in detail.…”

“…Based on above method, the Class Ф 2 inverter, as shown in Fig. 4, is proposed and is widely used in VHF power converters [52]- [57]. The topology can meet the soft switch requirement and effectively reduce the voltage stress across the switch.…”

A New Power Combining and Outphasing Modulation System for High-Efficiency Power Amplification

“…1). Because the two signals are of constant amplitude, they can be synthesized with highlyefficient PAs including partially-and fully-switched-mode designs such as classes D [3][4][5], E [6,7], F [8][9][10], E/F [11] and current-mode D [12], Inverse F [13], Φ [14,15], etc. (These amplifiers can be made highly efficient in part because they needn't have the capability to provide linear output control.)…”