Design of a BAW Quadplexer Module Using AWR Software
9 www.cadence.com/go/awr
The approximate width of the T-junction is 0.4mm and the width of the BPFs is about 4mm. To prevent width mismatch
between two transmission lines, tapered transmission lines were used. After adding these tapered lines, some lengths
needed fine tuning since the length of the tapered line affects circuit behavior. Figure 16 shows the S11 and S23 parameters,
which indicate reflection loss and isolation loss, respectively.
Figure 16: Reflection loss and isolation loss of the diplexer
It can be seen that the isolation of the bands has its lowest point at the transmission zero of the BPFs These properties
provided acceptable isolation for the diplexer. EM simulation results shows reflection loss of the signal at the B3 and B7
frequency bands is around -20dB. These values were considered realistic in order to have acceptable reflection loss after
manufacturing.
Figure 17 shows the insertion loss parameters of Ports 2 and 3, shown as the S21 and S31 parameters. Out-band rejection of
the diplexer is above acceptable. The lowest insertion loss for the in-band is around -0.4dB, which is an acceptable level of
insertion loss at that band. The simulation of the diplexer showed acceptable design parameters. The next step was to
combine the two duplexers to create the quadplexer.
Figure 17: Insertion loss of the diplexer
