Design of balanced dual-band bandpass filter with controllable bandwidths

A dual-band balanced bandpass filter (BPF) is proposed using stub-loaded resonators. Based on the theoretical analysis, it is found that the electrical performances of the differential-mode (DM), such as center frequencies and bandwidths can be controlled independently. The center frequency ratios of the two DM passbands can range from 1 to 2.6. The resonant frequencies of the common-mode (CM) are different from that of the DM, which helps to suppress the CM. Moreover, resistors are added in the middle of the resonator to enhance the CM suppression across the given frequency range. To verify the design method, a dual-band balanced BPF with controllable bandwidths and high CM suppression is designed, fabricated and measured. The measured result is in good agreement with the simulated result.

[1]  Pei-Yuan Qin,et al.  Compact Balanced Dual- and Tri-band Bandpass Filters Based on Stub Loaded Resonators , 2015, IEEE Microwave and Wireless Components Letters.

[2]  Fayu Wan,et al.  Stub-Loaded Theory and Its Application to Balanced Dual-Band Bandpass Filter Design , 2016, IEEE Microwave and Wireless Components Letters.

[3]  C.-I.G. Hsu,et al.  Balanced Dual-Band BPF With Stub-Loaded SIRs for Common-Mode Suppression , 2010, IEEE Microwave and Wireless Components Letters.

[4]  Q. Chu,et al.  Compact Dual-Band Bandpass Filters Using Open-/Short-Circuited Stub-Loaded $\lambda/4$ Resonators , 2015, IEEE Microwave and Wireless Components Letters.

[5]  Young-Ho Cho,et al.  Design of Balanced Dual-Band Bandpass Filters Using Asymmetrical Coupled Lines , 2013, IEEE Transactions on Microwave Theory and Techniques.

[6]  Li Yang,et al.  Balanced Dual-Band Bandpass Filter With Multiple Transmission Zeros Using Doubly Short-Ended Resonator Coupled Line , 2015, IEEE Transactions on Microwave Theory and Techniques.

[7]  Jia-Sheng Hong,et al.  Microstrip filters for RF/microwave applications , 2001 .

[8]  Quan Xue,et al.  Novel Balanced Dual-Band Bandpass Filter Using Coupled Stepped-Impedance Resonators , 2010, IEEE Microwave and Wireless Components Letters.

[9]  Quan Xue,et al.  Balanced Bandpass Filters Using Center-Loaded Half-Wavelength Resonators , 2010, IEEE Transactions on Microwave Theory and Techniques.

[10]  Quan Xue,et al.  Dual-Band and Wide-Stopband Single-Band Balanced Bandpass Filters With High Selectivity and Common-Mode Suppression , 2010, IEEE Transactions on Microwave Theory and Techniques.