Design of a BAW Quadplexer Module Using AWR Software
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Figure 20 shows the simulation results for the isolation of the system. The isolation was intended to be kept around -30dB;
therefore, the RX or TX signal does not over drive the front-end devices. S32 and S54 indicate the in-band isolation, while
S53, S52, S42, and S43 indicate the cross-band isolation.
Figure 20: Simulation results of the EM simulation for in-band and cross-band isolation
The simulation results were satisfactory and proved that the quadplexer had been designed correctly. After the layout of the
circuit was prepared, the next step was to design the layout of the circuit for manufacturing. In order to eliminate crosstalk of
the adjacent channels, the transmission lines to the ports were separated as much as possible. It was also important to
consider that the stepped impedance resonator could affect the resonance frequency. To prevent unintended resonance, the
resonators were carefully placed.
Measurement Results
Measurements were performed with a Rohde & Schwarz FSH8 vector network analyzer. Figure 21 shows the measurement
results for insertion loss. It can be seen that there is discontinuity at the B7 TX band, where the lowest performance was
achieved at around 2.66GHz.
Figure 21: Simulation results for insertion loss of the quadplexer
The final measurement was the isolation loss of the quadplexer. which is shown in Figure 22. Cross-band isolation is at a
satisfactory level, but in-band isolation is worse than the EM simulation result. In-band isolation is around -20dB, where
expected isolation is around -30dB.
Figure 22: Measurement results for isolation of the quadplexer
