Bulk acoustic wave resonator filters including rejection-band resonators
A BAW resonator filter can include a BAW resonator pass-band filter ladder, the BAW resonator pass-band filter ladder can be configured to pass frequency components of an input signal in a pass-band of frequencies received at an input node of the BAW resonator pass-band filter ladder to an output node of the BAW resonator pass-band filter ladder. A first rejection-band series resonator can be coupled in series between an input port of the BAW resonator pass-band filter ladder and the input node, the first rejection-band series resonator can have a first anti-resonant frequency peak in a rejection-band of frequencies that is less than the pass-band of frequencies. A second rejection-band series resonator can be coupled in series between an output port of the BAW resonator filter and the output node, the second rejection-band series resonator can have a second anti-resonant frequency peak in the rejection-band of frequencies.
1. A Bulk Acoustic Wave (BAW) resonator filter comprising:
a BAW resonator pass-band filter circuit, the BAW resonator pass-band filter circuit configured to pass frequency components of an input signal in a pass-band of frequencies received at an input of the BAW resonator pass-band filter circuit to an output of the BAW resonator pass-band filter circuit; and
a first rejection-band series resonator coupled in series with the input of the BAW resonator pass-band filter circuit or in series with the output of the BAW resonator pass-band filter circuit, the first rejection-band series resonator having a first anti-resonant frequency peak in a rejection-band of frequencies that is less than the pass-band of frequencies.
2. The BAW resonator filter of claim 1 wherein the BAW resonator pass-band filter circuit comprises a ladder topology, a lattice topology, or a modified lattice topology.
3. The BAW resonator filter of claim 2 wherein the BAW resonator pass-band filter circuit comprises a BAW resonator pass-band filter ladder and the first rejection-band series resonator is coupled in series with the input, the BAW resonator filter further comprising:
a second rejection-band series resonator coupled in series with the output, the second rejection-band series resonator having a second anti-resonant frequency peak in the rejection-band of frequencies.
4. The BAW resonator filter of claim 1 wherein the pass-band of frequencies is about 5.49 GHz to about 5.835 GHz.
5. The BAW resonator filter of claim 1 wherein the rejection-band of frequencies is about 5.17 GHz to about 5.33 GHz.
6. The BAW resonator filter of claim 3 wherein the first and second anti-resonant frequency peaks are in a range between about 5.17 GHz and about 5.33 GHz.