Improvement of Non-linear Performance in BAW Filters using Balancing Capacitors

Linearity requirements in BAW modules intensified drastically over the past years. While an optimized filter and module design can improve the overall floor of the non-linear response efficiently, often unavoidable effects of parasitics in a BAW chip require more advanced techniques to meet the part's specification requirements. In this article, we present a novel approach to further linearize the response of BAW modules using so called balancing capacitors on cascaded resonator stages. The basic principle of the balancing capacitor will be discussed. In addition, we will demonstrate the effect of a balancing capacitor in reducing spikes in the non-linear response using a statistical analysis to avoid the impact of part-to-part variation seen in on-wafer measurements.