Superconductor/nonlinear-dielectric bilayers for tunable and adaptive microwave devices

We have designed fabricated and characterized electrically tunable and adaptive microwave devices using coplanar waveguide (CPW) structures which incorporate bilayers of superconducting YBa₂Cu₃O_7-x and nonlinear dielectric SrTiO₃ on 1 cm × 1 cm x 0.5 mm LaAlO₃ substrates. The microwave devices include voltage-tunable phase shifters and delay lines voltage-tunable mixers and voltage-tunable and adaptive bandpass filters. Under dc voltage bias these compact CPW devices exhibit more than 360° relative phase shift at 2 GHz more than 30 dB tunability in mixed microwave power between 0.7 GHz and 5.9 GHz and fine-tunable symmetric filter profile at around 2.5 GHz with less than 2% bandwidth and more than 15% adaptive range.