A Distributed Phase Shifter Using Bi_1.5Zn_1.0Nb_1.5O₇/Ba_0.5Sr_0.5TiO₃ Thin Films

We report the demonstration of a monolithic phase shifter employing Bi_1.5Zn_1.0Nb_1.5O₇ (BZN)/Ba_0.5Sr_0.5TiO₃ (BST) thin films on sapphire substrates. The BST and BZN thin films are successively deposited by radio?frequency magnetron sputtering. A distributed phase shifter with a coplanar?waveguide transmission line periodically loaded with the BZN/BST capacitors is fabricated. The return loss of the circuit is better than -13 dB from 1 to 12 GHz, and it provides 65° phase shift with an insertion loss of -4 dB at 12 GHz. The results show that BZN/BST thin films are promising candidate dielectrics for rf/microwave tunable applications.