寬頻180°反射式數位移相器

Abstract

本論文前半部提出一個中心頻率為2.5GHz 的寬頻微波岔路環。此電路利用平衡式微帶線來激發並使用一個理想反相器取代一段二分之一波長傳輸線，可使頻寬接近120%和使體積縮小為原來的50%等優點。 本論文後半部份利用前半部分的寬頻微波岔路環實現一個中心頻率為2.5GHz 的180°寬頻反射式數位移相器。不同於傳統的反射式移相器將PIN二極體加在90°混成器上，把PIN二極體加在180°混成器並將兩個PIN二極體一順偏一反偏或一反偏一順偏可得頻寬更寬以及兩個狀態介入損失相接近的180°反射式移相器。此論文全部電路以微帶線型式製作在介電係數為3.58厚度為20mil的RO4003的基板上。

This thesis includes two parts. In the first part, the 180° hybrid ring with a center frequency of 2.5GHz and excited by the balanced microstrip line is designed. By replacing a half wavelength transmission line with an ideal phase inverter, the 180° hybrid ring exhibits a wide bandwidth of almost 120% and the size reduced for 50%. In the second part, by using the broadband 180° hybrid ring designed in the first part, the broadband 180° reflection type digital phase shifter has been realized. Unlike the conventional reflection type phase shifter where two PIN diodes are connected to a 90° hybrid ring with the same bias condition, in the proposed phase shifter two PIN diodes are connected to the 180° hybrid ring with opposite bias condition. The proposed one can get much wider bandwidth with almost the same insertion loss in two phase states. The whole circuits in this thesis are fabricated with microstrip line on a RO4003 substrate with a dielectric constant of 3.58, a thickness of 20 mil.