Technology enhancements for high performance BAW duplexer

In this article we will present the recent improvements in the performance of Solidly Mounted Resonator (SMR) high performance duplexer using Band2 duplexer for illustration purpose. Over the past 4 years insertion loss and rejection steepness were improved dramatically. Optimization of resonator intrinsic performance has played obviously a critical role but less expectedly the introduction of new building block (MIM capacitor) capitalizing on SMR technology has proven key for both performance improvement and size reduction. A new design approach based on the selective reduction of the effective coupling coefficient of certain resonators will be presented. We will discuss its impact on slope steepness improvement. The additional flexibility provided by this method enables as well to reduce further the impedance variation presented on the transmit path. This feature is critical to maintain high efficiency and linearity of any Power Amplifier upfront in the chain.