Superconducting tunable filter with constant bandwidth using coplanar waveguide resonators

Abstract

In this paper we propose a two-pole varactor-tuned superconducting filter using coplanar waveguide (CPW) spiralin-spiral-out (SISO) resonators. Novel internal and external coupling structures are introduced to meet the requirements for a tunable filter with a constant absolute bandwidth. The fabricated device has a frequency tuning range of 14.4% at frequencies ranging from 274.1 MHz to 317.7 MHz, a 3-dB bandwidth of 5.14 ± 0.06 MHz, and an insertion loss of 0.08 dB-0.70 dB. The simulated and measured results are in excellent agreement with each other.

Five‐order narrow‐band tunable superconducting filter

“…At present, superconducting filters have been used in many places, such as weather radar, space communication, and astronomical exploration . Among them, the tunable frequency filter has an indispensable effect on the multiband communication system, and there are many design methods to tune the center frequency of the filter: Sekiya et al Placed an additional pad on the open end of the resonator to adjust the center frequency of the filter; Jiang et al proposed a bipolar varactor diode on a coplanar waveguide spiral output resonator to tune the center frequency of the filter; Ohsaka et al proposed using a dielectric tuning plate to change the center frequency of the filter and so on. For current research work, most tunable filters operate at frequencies above 300 MHz or above 3‐order.…”