Development and Design of Asymmetric Bandwidth Closely Dual-Band Filters

• Main Authors: CYONG-YIN, SYU, 許瓊尹
• Other Authors: CHEN, CHU-YU
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/14151136691985560730

碩士 === 國立臺南大學 === 電機工程學系碩博士班 === 105 === The main purpose of this paper is to develop and design the closely dual-band filter with asymmetric bandwidth. They are implemented on the printed circuit board. In the first part of this thesis, the LTE / LTE-Advanced specifications for closely dual-band are introduced. The relationship between the LTE/LTE-Advanced and 3GPP system is described and explained. Then, the coupled half-wavelength microstrip line is proposed. The coupling mechanism is analyzed based on the current distribution. In the second part, the architecture of both Open-Loop Resonators (OLRs) and Inter-digital Capacitor Resonators (IDCRs) are demonstrated and analyzed. The impedance ratio of Half-wavelength OLRs and the external quality factor for each feeding position are used to control the bandwidth. The overall bandwidth covering the range of LTE / LTE-Advanced Band1 uplink and downlink is required. Then, the design of IDCRs can provide another coupling path to suppress the specified frequency. The parameters such as interdigital length (I_L ), interdigital number (N) and transmission line width ( T_w ) at the resonant frequency are simulated. Multiple parameters in the structure of IDCRs can provide high freedom of design. The IDCRs with compact size are embedded in the half-wavelength OLRs, and the suppression band is formed in the passband to produce the extremely closely dual passbands. By adjusting the distance between the inner and outer rings, the coupling ability can be adjusted to control the suppression bandwidth. To verify this approach, a prototype dual-band filter is designed and fabricated. The resonant frequencies are operated at 1.95 GHz and 2.11 GHz, respectively. The frequency ratio of 1.084 for the higher passband to the lower passband is achieved. The FBW are 8.1% and 4.7%, respectively. The insertion loss S_21 of suppression band is 21 dB. It can be applied in LTE / LTE- Advanced Band 1 networks. In the third part, the previous concept is applied to design a multiplexer with four bands. The both LTE / LTE-Advanced band 1 and band 7 are illustrated. The energy transmission using tapped-line method and coupled method is demonstrated. Finally, a multiplexer with compact size is implemented. To introduce the design concept to automobile electronic band, the 60 GHz and 77 GHz dual-passband filter using the 0.18 μm CMOS technology is proposed. In this thesis, the designed structures are simulated with the full-wave electromagnetic simulation software Zeland-IE3D. It shows that simulation and measurement results are have a good agreement.