Synthesis of Fully Canonical Wideband Bandpass Filters With Complex Reflection Zeros

Yu Zhu,Yong Fan,Kaijun Song

doi:10.1109/access.2019.2928342

Abstract

The paper presents a synthesis of fully canonical wideband bandpass filters with complex reflection zeros (RZs), which can realize the bandpass filters with the same number of transmission zeros (TZs) as the order of filters. Three functions are proposed to generate the general Chebyshev filtering function with complex RZs. A simple recursion technique is described for the generation of the polynomials for the filtering function with symmetrically or asymmetrically prescribed TZs. Then, a method for the direct extracting the elementary lumped elements of the modified inline topology circuit to yield a prescribed response is given. Two design examples demonstrating the soundness of the synthesis method are presented and one of them is implemented, fabricated, and measured.

Highlights

In the modern wireless communication systems, the radio frequency and microwave filter is one of the key passive components, which attracts great attentions from both academic and industrial communities
To meet the demands of filters with high performances from the rapid development of radio frequency systems, lots of efforts have been taken in researches about filters [1]–[19]
F1 (ω1) = ε0F1t (ω1) = −1 F1 (ω2) = ε0F1t (ω2) = 1. (6). These functions can synthesize the fully canonical bandpass filters with arbitrary bandwidth, the roots of reflection polynomial are constrained to lie on the imaginary axis

Summary

INTRODUCTION

In the modern wireless communication systems, the radio frequency and microwave filter is one of the key passive components, which attracts great attentions from both academic and industrial communities. Many new technologies about filters are presented, such as stepped impedance resonator [1], [2], multiple-mode resonator [3]–[5], composite right/left handed transmission line [6], defected ground structure [7], and substrate integrated waveguide technology [8]–[10] These technologies contribute to designing filters and introduce some attractive features, such as low insertion loss, easier manufacture, compact size and wide stopband. A general approach to the synthesis of fully canonical wideband bandpass filters with complex RZs is proposed. Y. Zhu et al.: Synthesis of Fully Canonical Wideband Bandpass Filters With Complex RZs function with complex RZs. Secondly, a simple recursion technique to compute the polynomials for this filtering function is presented. Two design examples are synthesized and one of them is designed, fabricated to validate the above synthesis principle

GENERAL CHEBYSHEV FILTERING FUNCTION WITH COMPLEX REFLECTION ZEROS

NEW FILTERING FUNCTION WITH COMPLEX

MODIFIED LUMPED ELEMENT CIRCUIT TOPOLOGY AND EXTRACTING METHOD

Afr s Cfr

DESIGN EXAMPLES

CONCLUSION