Hybrid acoustic LC filter with harmonic suppression
Aspects of this disclosure relate to hybrid acoustic LC filter with harmonic suppression. The hybrid acoustic LC filter includes a hybrid passive/acoustic and a non-acoustic LC filter cascaded with the hybrid passive/acoustic filter. The hybrid passive/acoustic filter can be configured to filter a radio frequency signal. The hybrid passive/acoustic filter can include acoustic resonators and a non-acoustic passive component. The non-acoustic LC filter can be configured to suppress a harmonic of the radio frequency signal. The non-acoustic LC filter can be a low pass filter or a harmonic notch filter, for example. Related multiplexers, wireless communication devices, and methods are disclosed.
1 . A hybrid acoustic LC filter with harmonic suppression, the hybrid acoustic LC filter comprising:
a first hybrid passive/acoustic filter including at least first and second acoustic resonators, the first acoustic resonator in parallel with a first inductor, the first acoustic resonator and the first inductor in series with a second inductor, at least a first capacitor and a third inductor connected in parallel with the first and second acoustic resonators, and at least a second capacitor in parallel with a fourth inductor, the second capacitor and the fourth inductor connected in parallel with at least the second acoustic resonator; and
a non-acoustic LC filter cascaded with at least the first hybrid passive/acoustic filter, the non-acoustic LC filter in electrical communication with an input and including at least a first LC resonant circuit connected to a series LC tank, a first bridge capacitor coupled to the input and the series LC tank.
2 . The hybrid acoustic LC filter of claim 1 wherein the non-acoustic LC filter is a notch filter.
3 . The hybrid acoustic LC filter of claim 2 wherein a frequency response of the notch filter has a notch corresponding to a second harmonic of a radio frequency signal.
4 . The hybrid acoustic LC filter of claim 2 wherein a frequency response of the notch filter has two notches corresponding to different harmonics of a radio frequency signal.
5 . The hybrid acoustic LC filter of claim 1 wherein the non-acoustic LC filter is a band pass filter.
6 . The hybrid acoustic LC filter of claim 1 wherein the non-acoustic LC filter includes integrated passive devices of an integrated passive device die.
7 . The hybrid acoustic LC filter of claim 1 further comprising a second hybrid passive/acoustic filter with an output connected to the output of the first hybrid passive/acoustic filter at a common node, the first hybrid passive/acoustic filter including a first carrier and the second hybrid passive/acoustic filter including a second carrier to support carrier aggregation at the common node.
8 . The hybrid acoustic LC filter of claim 1 wherein at least one of the first and second acoustic resonators include bulk acoustic wave resonators.
9 . The hybrid acoustic LC filter of claim 1 wherein the first and second acoustic resonators include a first shunt acoustic resonator and a second shunt acoustic resonator.
10 . A multiplexer comprising:
a first filter configured to filter a radio frequency signal, the first filter including a hybrid passive/acoustic filter and a non-acoustic LC filter cascaded with the hybrid passive/acoustic filter, the hybrid passive/acoustic filter including at least first and second acoustic resonators, the first acoustic resonator in parallel with a first inductor, the first acoustic resonator and the first inductor in series with a second inductor, at least a first capacitor and a third inductor connected in parallel with the first and second acoustic resonators, and at least a second capacitor and a fourth inductor further connected in parallel with at least the second acoustic resonator, and the non-acoustic LC filter in electrical communication with an input and including a first LC resonant circuit connected to a series LC tank, and a first bridge capacitor coupled to the input and the series LC tank; and
a second filter coupled to the first filter at a common node.
11 . The multiplexer of claim 10 wherein the second filter includes at least a third acoustic resonator.
12 . The multiplexer of claim 11 wherein the first filter is a mid-band filter and the second filter is a high band filter.
13 . The multiplexer of claim 12 further comprising a low band filter coupled to the first filter and the second filter at the common node.
14 . The multiplexer of claim 10 wherein the non-acoustic LC filter includes integrated passive devices of an integrated passive device die.
15 . The multiplexer of claim 10 wherein the non-acoustic LC filter is a notch filter.
16 . The multiplexer of claim 10 wherein the first and second acoustic resonators include a first shunt acoustic resonator and a second shunt acoustic resonator.
17 . The multiplexer of claim 10 wherein the first and second acoustic resonators include bulk acoustic wave resonators.
18 . A wireless communication device comprising:
a radio frequency front end including a filter configured to filter a radio frequency signal, the filter including a hybrid passive/acoustic filter and a non-acoustic LC filter cascaded with the hybrid passive/acoustic filter, the hybrid passive/acoustic filter including at least first and second acoustic resonators, the first acoustic resonator in parallel with a first inductor, the first acoustic resonator and the first inductor in series with a second inductor, at least a first capacitor and a third inductor connected in parallel with the first and second acoustic resonators, and at least a second capacitor in parallel with a fourth inductor, the second capacitor and the fourth inductor connected in parallel with at least the second acoustic resonator, and the non-acoustic LC filter in communication with an input and including a first LC resonant circuit connected to a series LC tank, and a first bridge capacitor coupled to the input and the series LC tank; and
an antenna in communication with the radio frequency front end, the antenna configured to transmit a filtered version of the radio frequency signal.
19 . The wireless communication device of claim 18 configured as a mobile phone.
20 . The wireless communication device of claim 18 further comprising a baseband processor and a transceiver, the transceiver being in communication with the radio frequency front end and also being in communication with the baseband processor.