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

Microwave devices using coplanar waveguide (CPW) structures which incorporate bilayers of superconducting YBa/sub 2/Cu/sub 3/O/sub 7-x/ and nonlinear dielectric SrTiO/sub 3/ on 1 cm/spl times/1 cm/spl times/0.5 mm LaAlO/sub 3/ 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/spl deg/ 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.