Search

This study proposes a high-temperature superconducting (HTS) bandpass filter with a continuously tunable bandwidth and center frequency. The proposed filter combines several gallium arsenide varactors and a dual-mode resonator (DMR). The even and odd modes of the DMR can be tuned simultaneously using a single bias voltage. The capacitive value of varactors in the circuit is tuned continuously under continuous voltage and frequency tunability. External couplings and the interstage can be realized using an interdigital coupling structure; a fixed capacitor is added to the feeder to improve its coupling strength. A low-insertion loss within the band is obtained using HTS technology. Additionally, the proposed filter is etched on a 0.5 mm-thick MgO substrate and combined with YBCO thin films for demonstration. For the as-fabricated device, the tuning frequency range of 1.22~1.34 GHz was 9.4%; the 3-dB fractional bandwidth was 12.95~17.39%, and the insertion loss was 2.28~3.59 dB. The simulation and experimental measurement results were highly consistent. [ABSTRACT FROM AUTHOR]

This study proposes a high-temperature superconducting (HTS) bandpass filter with a continuously tunable bandwidth and center frequency. The proposed filter combines several gallium arsenide varactors and a dual-mode resonator (DMR). The even and odd modes of the DMR can be tuned simultaneously using a single bias voltage. The capacitive value of varactors in the circuit is tuned continuously under continuous voltage and frequency tunability. External couplings and the interstage can be realized using an interdigital coupling structure; a fixed capacitor is added to the feeder to improve its coupling strength. A low-insertion loss within the band is obtained using HTS technology. Additionally, the proposed filter is etched on a 0.5 mm-thick MgO substrate and combined with YBCO thin films for demonstration. For the as-fabricated device, the tuning frequency range of 1.22~1.34 GHz was 9.4%; the 3-dB fractional bandwidth was 12.95~17.39%, and the insertion loss was 2.28~3.59 dB. The simulation and experimental measurement results were highly consistent.

This paper presents a miniaturized dual-band bandpass filter using two coupled dual-moderesonators (DMRs). The dual-mode resonator is a short-circuited stub loaded square loop resonator. The concept of miniaturization achieved using multilayered technology. Therefore, the filter circuits are achieved in three layers. On the first layer, two coupled dual-mode resonators are designed and shorted to a ground layer to specify the required passbands. Next, a second layer employs two shorted quarter wavelength stubs coupled through one via hole are capacitively coupled to the first layer circuit to achieve the filtering response. For our demonstration, a multi-band bandpass filter is designed to serve a multifunctional wireless system has centre frequencies of 1.9 GHz GSM and 3.5 GHz WiMax systems. The filter is implemented and simulated using the momentum simulator of the Advanced Design System (ADS) software package. The filter response has two second-order passbands with four transmission zeros leads to a high skirt selectivity. The filter circuit area is very small, less than 37 mm2 terminating the feeding ports.