Thin film resonator (TFR) low insertion loss filters

Progress on the TFR SCF (stacked crystal filter) configurations is reported including device performance, modeling, design, and materials requirements. Both Si- and GaAs-substrate-based filters are reported with GaAs receiving increased emphasis for microwave integrated circuit applications. The experimental results reported are the result of a number of device feasibility studies done in the course of developing the technology toward its fully integrated form. Filters having insertion losses less than 1.6 dB, with two pole equivalent responses, have been demonstrated at frequencies between 1 and 2 GHz. These filters, using aluminum nitride as the piezoelectric, are approximately 1 mm² in area and designed for a 50-Ω impedance level