Superconducting filters based on mixed resonators

Abstract

In high-temperature superconducting (HTS) microwave filters, the requirements for miniaturization and high power handling are difficult to match simultaneously. In this paper, we report on the design and realization of HTS filters realized by combining dual-mode cross-slotted and stepped resonators in order to obtain a compact size and a relatively high power handling. Prototype HTS four-pole filters operating in C-band and L-band, with quasi-elliptical responses, on both MgO and LaALO 3 substrates, have been designed and tested at T = 77 K. The filters present a high degree of miniaturization as they save more than 50% of the area compared with those realized with dual-mode and/or hairpin resonators. The measured responses agree well with the simulation even if the in-band ripple should be optimized. As far as the power handling is concerned, the C-band filter grown on LaAlO 3 presents a power handling of P in = 20 dBm limited by the power handling of the dual-mode cross-slotted resonator, while we have observed no power degradation in the L-band filter grown on MgO up to P in = 33 dBm limited by power supply.

HTS miniaturized filter based on mixed resonators integrated with a two-stage low-noise amplifier

“…A detailed description of the filter performances is reported elsewhere [9,10]. Briefly, it consists of a four-pole filter, realized by using stepped impedance and miniaturized dualmode resonators.…”

“…In this paper, we report on the integration in a single metallic box of an HTS miniaturized filter, developed in our previous works [9,10], with a maximum power handling of 33 dBm (2 W), and a cryogenic two-stage low-noise amplifier with a gain of about 30 dB. The fabricated device operates in the L-band where modern mobile communication systems operate.…”

Third-order intermodulation measurements of 2 GHz microstrip bandpass filters based on high-temperature superconductors

“…Until recently, however, microstrip filters were not used in the transmitters because of the powerhandling limitations set by nonlinear effects [3]. Several HTS filters for high-power-handling operation have been reported [4][5][6] but their configurations are much different from those for the microstrip filters successfully used in the receiver systems [1,2] and are not suitable for realizing highly integrated miniaturized filters with a few tens of resonators.…”