HTSC Cascaded Linear-Phase Filter with Quasi-Elliptic Response

In view of the difficulty of designing a high-order linear phase filter with prototype parameters directly, this paper proposes a new approach to rapidly construct a high order linear phase filter through cascading two same low-order linear phase filters. A twelve-order HTSC cascaded linear phase filter is fabricated on YBCO/LaAlO3/YBCO substrate with the dimension of 44.1mm ×31.4mm. The measured result shows that the filter has a 56 MHz passband at a center frequency of 1993 MHz. The minimum insertion loss in the passband is 0.59 dB. The group delay variation in passband is less than 5 ns over 78.5% of the filter bandwidth which is in good agree with the simulation result.