使用局部阻抗匹配及濾波器設計之毫米波頻段覆晶轉接

Abstract

本篇論文中提出了三種不同基板間的轉接設計，分別應用於77GHz汽車防撞雷達系統以及60GHz無線通訊系統，在77GHz汽車防撞雷達系統中，轉接設計是在低溫共燒陶瓷基板以及鐵氟龍基板間，而60GHz無線通訊系統則是使用兩種不同的平面電路板進行設計。轉接設計皆是用覆晶結構。 第一種轉接屬於傳統的轉接設計，兩個基板上的微帶線利用錫球直接連接，並使用局部阻抗匹配的方式進行補償設計，此種設計方式的插入損耗大約為1dB並具有寬頻轉接的特性。 第二種則是以微帶線耦合濾波器的概念設計轉接，以微帶線作為共振器，分別放置於兩個基板上，並使用覆晶的方式，讓微帶線產生垂直耦合，達到微帶線耦合濾波器的設計。 第三種轉接是以矩形共振腔及基板合成波導的方式進行濾波器設計，兩個基板分別使用連通柱形成矩形共振腔，而兩基板間的空氣部分為另一矩形共振腔，以三階柴比雪夫濾波器來設計，以開槽的方式進行耦合。利用矩形共振器提高品質因子，使濾波器響應之插入損耗降低，即改善轉接部分的損耗。由於利用濾波器的概念結合轉接的功能，使整個結構具有濾波器的響應，也具有轉接的功能，而且僅剩下濾波器的損耗，亦達到降低轉接損耗的目的。

This thesis proposes three types of transitions between different substrates, applied separately for 77GHz automotive collision avoidance radar systems and 60GHz wireless communication systems. The 77GHz automotive collision avoidance radar system is developed using LTCC and Teflon substrates, while 60GHz wireless communication system is realized in two different printed circuit boards. The transitions are all designed with flip-chip structures. The first design adopts the traditional flip-chip structure, with the microstrip lines on the substrates directly connected by bumps. Using the idea of locally matching, the method achieves a wideband transition with about 1 dB insertion loss. The second type of transition is designed by the concept of the microstrirp coupled-resonator filter. The microstirp resonators are located on the two types of substrates, while the transition is implemented by the vertically coupling with the coupling coefficients according to the design specification. The third transition is developed by substrate integrated waveguide and the side walls of the cavities are realized by vias. There are three cavities: two different substrates implement two cavities resonators, respectively, while the air between two substrates forms the third resonator. A 3rd-order Chebyshev bandpass response is chosen to validate the design concept, using slots between the cavities as the coupled mechanism. The design further decreases the loss by using the high-Q cavity resonators. Since the design combines transitions and the filter function using the coupled-resonator concept, it can achieve the filtering responses and decrease the overall loss of the system.