Broadband Switch-Mode Radio Frequency Power Amplifiers using Tunable Ferroelectric Thick-Film Components

本项目包括射频放大器用新型铁电(钛酸锶)变容二极管在高频高功率下的热效应的基础研究。此外，一个主要目标是实现高效的射频和直流去耦合以实现动态偏置。这一目标是通过改进的变容二极管布局来实现的，在单层和多层结构中，通过同时考虑耦合的电和热性能，以及通过使用不同的厚膜和块体陶瓷的材料制备方法来实现。特别注意通过使用替代基板材料和高功率封装来降低热阻。特别是高功率封装需要专门的研究，因为它影响设备的电气和热性能。在大信号工作条件下，将对新型变容二极管进行建模、表征和优化。为了能够在不同温度和不同功率水平下模拟可调谐电路，将开发可靠的模型。作为概念验证，将在输出功率高达50W的GaN-HEMT基功率放大器中集成可调谐匹配网络的演示器将被设计用于0.9到3.0 GHz的电信频段。可调谐功率放大器的效率和线性度将首次在高达20 MHz带宽的信号下进行研究。新的变容二极管偏置和射频和直流解耦将在动态操作中实现，并将首先在大规模操作中使用双音信号来研究动态行为。

This project covers fundamental investigations on thermal effects in novel ferroelectric (Barium Strontium Titanate) varactors for RF amplifiers when exposed to high power at high frequencies. In addition, one major objective is to achieve efficient RF- and DC-decoupling for dynamic biasing. This is aimed to be accomplished by enhanced varactor layouts, in uniplanar as well as multilayer structures by considering coupled electrical and thermal properties at the same time, and by using different material preparation methods for thick-film and bulk ceramics. Special attention is put to reduce thermal resistance by using alternative substrate materials and a high-power package. Especially the high-power package requires dedicated investigations, as it influences the electrical as well as thermal properties of the device. The novel varactors will be modeled, characterized and optimized under large signal operation. Reliable models will be developed to enable simulation of tunable circuits at different temperatures as well as different power levels.As a proof-of-concept, a demonstrator integrating tunable matching networks into GaN-HEMT based power amplifiers with output power up to 50 W will be designed for a telecom band in the 0.9 to 3.0 GHz range. Efficiency and linearity of the tunable power amplifier will be investigated with signals up to 20 MHz bandwidth for the first time. Novel varactor biasing and RF- and DC-decoupling will be realized for dynamic operation and first dynamic behavior will be investigated using two-tone signals in large-scale operation.