HTS-based switched filter banks and delay lines

A thermal switch has been developed that provides good isolation and insertion loss with adequate switching times to allow a monolithic approach to the switched lines and filter banks. Filter banks in the 8-11-GHz range have been demonstrated with insertion losses of < 1 dB and out-of-band rejection greater than a package-limited 50 dB. Switched delay lines have been fabricated with insertion losses less than 0.3 dB/b and peak phase deviations from linearity of less than 5 degrees over 30-GHz bandwidths. The materials and substrate dependencies of the performance are analyzed, and there generally is a trade-off between RF power handling and switching speed/control power requirements. Devices made with TlCaBaCuO tend to switch faster and consume less power than YBaCuO devices because of the effects of flux dissipation. For the same reason, the RF power handling ability of the TlCaBaCuO devices is worse. YBaCuO devices grown on sapphire switch faster than do those on LaAlO/sub 3/ because of substrate properties but do require additional DC power.<>