新型LTCC微波传输线谐振器的小型化建模及应用研究

LTCC (low temperature co-fired ceramic) technology has recently attracted much attention as it can be effectively used to achieve compact size, light weight and high performance in various microwave components and devices. In the past, many LTCC circuits, such as filters, were conventionally implemented using three design methods, i.e. lumped element, semi-lumped element and distributed element. The first two, nevertheless, are usually only good in lower frequency ranges. Design method involving distributed element, which is applicable in higher frequency ranges, can significantly facilitate the microwave circuit designs for various application. However, the distibuted circuit size is always too large. In view of this point, this project aims at conducting the research on the modeling of compact LTCC transmission line resonator, along with exploring its applications in various LTCC components and circuits. Half-wavelength stripline resonator is regularly and symmetrically folded in the horizontal and vertical directions for modeling a three dimension (3-D) compact transmission line resonator. Because of the inner slow wave effect of the proposed resonator, its size reduction can be enhanced. The approaches and guidelines of the modeling are extensively investigated in this project to study this resonator. The symmetrical plane of the structure becomes a virtual ground that is very useful for accurate design and theoretical analysis of the proposed resonator. The proposed resonator is applied to design compact single-ended, balanced, and balun filters for meeting various requirements. It is worth-mentioning that a complete study will be conducted to further explore new applications of this resonator for the microwave active circuits. By using Surface Mounting or Embedding Technology, the IC chips can be loaded onto a resonator to form a compact tunable resonator, and then it is used to design various tunable filtering circuits and voltage controlled oscillators (VCOs) for further expanding the applications of the proposed compact resonator. The practicality value of the proposed LTCC miniaturized transmission line resonator can be easily seen here.

低温共烧陶瓷（LTCC）技术是实现微波元器件及组件小型化、轻量化和高性能的有效方法。在以往的LTCC电路（如滤波器）设计中，设计方法主要可以分为三类：集总、半集总、分布参数法。前两种方法主要适用于较低频段；分布参数法适用于高频且可简化电路设计，但电路体积往往过大。鉴于此，本课题将开展LTCC传输线谐振器小型化建模及其应用研究。通过在水平和垂直两个方向上对半波长带状线谐振器进行有序对称弯折，同时利用其内部存在的慢波效应，构建三维紧凑的传输线谐振器模型，并提出建模方法和准则。对称面形成的虚拟地将有利于该谐振器的精确建模和特性分析。进而利用该谐振器设计出结构紧凑的各种单端/平衡/巴伦式滤波电路以满足不同的需求。同时深入探索其在微波有源电路中的应用，通过表面贴装或内埋IC芯片，设计出小型化的电调谐振器，并应用在各种电调滤波电路和压控振荡器中，拓展该谐振器的应用范围，凸显其实用价值。

随着现代通信技术的快速发展，通信系统迫切需要微波电路和组件的小型化、轻量化和高性能。为了满足这一需求，低温共烧陶瓷（LTCC）技术作为一种高密度集成技术被广泛应用于微波电路和组件的设计。在以往的LTCC电路设计中，设计方法主要可以分为三类：集总、半集总和分布参数法。前两种方法主要适用于低频段和窄带设计；分布参数法适用于高频段（如毫米波频段）且电路设计方法简单，但电路体积往往过大。因此，本课题将利用分布参数法开展LTCC传输线谐振器小型化建模及其应用研究。.研究内容主要包括：（1）开展了半波长谐振器在LTCC三维多层空间中小型化建模的研究。提出了小型化建模的准则：每层弯折后的带状线都要有与之对应的实际地和虚拟地，形成完整的信号回路，保证谐振器的电性能基本不变。（2）研究了微波无源滤波电路。A.LTCC双模滤波器：通过在小型化谐振器模型上加载枝节构成双模谐振器，设计出了迄今为止最小的LTCC分布式滤波器，尺寸与集总滤波器几乎相同。进而设计了LTCC宽带分布式滤波器。B. LTCC毫米波双通带滤波器：首次发现了阶跃阻抗谐振器上存在谐波的电压零点，该零点被用来加载枝节，实现滤波器两个通带的独立可控。C. 平衡/巴伦式滤波器：利用半波长谐振器基波电压呈奇对称这一特性，设计了平衡/巴伦式滤波器。利用高温陶瓷介质谐振器拓展研究了高性能平衡/巴伦式滤波器。（3）研究了微波有源电路。首次提出了电调谐振器中二极管（可变电容）的加载原理和宽带调谐方案。通过在LTCC表面贴装二极管设计了通带可调和可开关的电调滤波器；通过研究宽带耦合和馈电方案，设计出了通带频率调谐范围达到84.4%的电调滤波器，取得了重要的技术突破。在振荡器设计中，将滤波器作为放大器的反馈回路，提高回路的复数品质因数，微波振荡器的相位噪声性能得到明显提高。.上述研究内容均通过了仿真和实验验证，达到预期目标，取得的成果具有重要的科学意义和工程应用价值，也可为后续的LTCC电路的研究与应用提供技术参考。