Addressing 5G NR Filter Challenges with Hybrid Technologies

The demand for high data rate and low latency is pushing the 5G. RF front end becomes more and more complicated with the new higher-frequency bands, increasing complexity of modulation schemes, and carrier aggregation (CA). It poses great challenges for designing filters to meet the diversified requirements in terms of performance, size, and cost. Acoustic filters like SAW and BAW are the dominant technologies for narrow RF bandwidth filtering. However, it is difficult to realize wide bandwidth filters due to their limited electromechanical coupling coefficient. On the other hand, LC filters like LTCC and IPD are suitable for wider bandwidth applications, e.g., carrier aggregation diplexer and low pass filtering. In this paper, a hybrid filter with FBAR and IPD is developed to achieve wider bandwidth compared to a single FBAR filter. It also has the advantage in terms of insertion loss, out-of-band rejection, nonlinearity, and power capability. A Band N41 filter is used to illustrate the advantages. The EDA design flow for such a hybrid filter has been developed, which helps to shorten the design cycle and ensure first-pass design success.