AWR Application Notes

Design of a BAW Quadplexer Module Using AWR Software 2 www.cadence.com/go/awr CA Technology Figure 1 shows the general working structure of CA technique. Figure 1: Working mechanism of the CA (image courtesy of Qorvo) CA technology can incorporate carriers of different (inter-band) frequency bands, as well as carriers of the same (intra-band) frequency bands, and carriers in the same frequency band can be either intra-band contiguous or non-contiguous. The easiest way to arrange aggregation would be to use contiguous component carriers within the same operating frequency band (as defined for LTE), called intraband contiguous. This might not always be possible, due to operator frequency allocation scenarios, in which case non-contiguous carriers can be employed. In fact, non-contiguous frequency allocation is the more commonly-used technique, which is advantageous since filter technology used for separating carriers often performs better for non-contiguous signals than for contiguous signals. In addition, it is far more difficult to use inter-band (different band) carriers since processing these signals requires complicated and advanced TX and RX structures. Figure 2 shows frequency allocation of the intraband and interband carriers. 1 Figure 2: Allocation of the intra-band contiguous (left) and inter-band carriers (right) (image courtesy of Qorvo) BAW Filter Technology BAW technology enables designers to create narrowband filters with exceptionally steep filter skirts and excellent rejection. This makes BAW the technology of choice for many challenging interference problems. BAW delivers these benefits at frequencies above 1.5GHz up to 6GHz and is used for many of the new LTE bands above 1.9GHz, making it a complementary technology to surface acoustic wave (SAW), which is most effective at lower frequencies, but scaled down in size. A piezo- electric film is sandwiched between two metal films as shown in Figure 3. The equivalent Butterworth/VanDyke circuit model consists of a fixed structure capacitance in parallel with a frequency dependent electro-mechanical resonant circuit. In the Van Dyke model 2 shown in Figure 3 (left), the series and parallel cascaded BAW resonators are arranged in a ladder configu- ration. The passband frequency is tuned by modifying the shunt resonators. Figure 3: BAW resonator (left) and BAW cross-section (right) of a Van Dyke model

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