Effect of DC biasing on YBCO/STO/LAO tunable microstrip filters

One or the critical design aspects in ferroelectric tunable microstrip Filt ers is choosing the: right bias configuration, for large tunability as well as to maintain the filter's passband characterisitics . This work based on strontium titanate (STO) ferroelectric thin-film based tunable microstrip filters for cryogenic temperature applications. Large tunability factors ha ve been demonstrated in YBCO/STO/LAO two-layered microstrip filters when op erated at or below 77 K. The effect of the do electric field (primarily res ponsible For tuning) and critical design parameters such as the insertion l oss, frequency tunability, return loss, and bandwidth of superconductor/fer oelectric/dielectric microstrip tunable K-band microwave filters is discuss ed in this work.