On the design of an FBAR PCS duplexer in LTCC chip-sized package

The paper reports about new results of a first-time attempt to utilize the existing design flow and methodology of surface acoustic wave (SAW) components to design film bulk acoustic resonator (FBAR) components. Due to the modular design of the computer aided design (CAD) environment, we could reuse many modules. In combination with new FBAR-specific modules, we obtained an FBAR-suitable CAD environment. Designing an FBAR personal communication system (PCS) duplexer comprising a low temperature co-fired ceramic (LTCC) chip sized package with integrated matching circuitry as well as the Rx- and Tx-filters we demonstrate the fitness for use of the new CAD environment. Starting from scratch the parts of the duplexer have been optimized with respect to each other. The experimental results of this design are presented indicating excellent performance especially regarding the Tx isolation. This most critical specification item has typically excelled with about 55 dB. Other specification items, such as, e.g., matching as well as pass band and stop band attenuation are also met. Measurement and simulation are in good agreement.