MICROWAVE PROPERTIES OF SR0.5BA0.5TIO3 THIN-FILM INTERDIGITATED CAPACITORS

Interdigitated capacitors have been fabricated on ferroelectric thin f ilms of Sr0.5Ba0.5TiO3. These devices have been characterized at micro wave frequencies from 50 MHz to 20 GHz, and have a 3.4:1 tuning range over a 1-40 V bias range. This is shown to originate from a relative d ielectric constant tuning of 3.8:1. The microwave losses exhibited by these capacitors are comparable to those of commercially available sem iconductor varactors for frequencies greater than 1 GHz, and should be useful for tunable microwave circuits in some 300 K applications. (C) 1998 John Wiley & Sons, Inc.