Multi-Technology Integration in Mixed-Mode Electronics - Technologies to Develop High-Q Tunable Filters

摘要

The technical work in this contract was focused on demonstrating the feasibility of creating a tunable high-Q filter in the 600 MHz to 900 MHz range. Applications include ELINT/SIGINT and wireless communications systems and mitigation of co-site problems in frequency agile military communications systems. The building blocks for the high-Q filter are a thin film high temperature superconducting (HTS) microstrip circuit with a variable capacitor inserted as a tunable element. The requirements on the variable capacitor are a high level of controllable behavior, the proper range of capacitance to tune the circuit, and low loss in the capacitor so as not to compromise the Q of the HTS filter. We evaluated several variable capacitor designs and fabricated device prototypes for evaluation, characterization, and integration with HTS resonator circuits. We made progress in several fundamental areas including the design of a fixed resonator to accommodate a variable element to provide a single-pole tunable filter, the analysis of filter response including loss mechanisms, and strategies to integrate these two technologies. Our results show that tilters with unloaded Q's in the range of 10,000 to 20,000 can be fabricated and tuned over 20% of their center frequency using our approach.