Acoustic wave filter with second harmonic emission suppression
View Patent ↗Aspects of this disclosure relate to acoustic wave filters with second harmonic emission suppression. In an embodiment, an acoustic wave filter includes a first pair of bulk acoustic wave resonators in anti-series with each other, a second pair of bulk acoustic wave resonators in anti-series with each other and having reverse electrode polarization relative to the first pair of bulk acoustic wave resonators, and a capacitor connected to a common electrode of a first bulk acoustic wave resonator and a second bulk acoustic wave resonator of the first pair of bulk acoustic wave resonators. Such an acoustic wave filter can provide second harmonic emission suppression. Other embodiments of acoustic wave filters with second harmonic emission suppression are disclosed. Related multiplexers, radio frequency modules, wireless communication devices, and methods are disclosed.
1 . An acoustic wave filter with second harmonic emission suppression, the acoustic wave filter comprising:
a first pair of bulk acoustic wave resonators in anti-series with each other, the first pair of bulk acoustic wave resonators including a first bulk acoustic wave resonator and a second bulk acoustic wave resonator;
a second pair of bulk acoustic wave resonators in anti-series with each other, the second pair of bulk acoustic wave resonators being in parallel with the first pair of bulk acoustic wave resonators, and the second pair of bulk acoustic wave resonators having reverse electrode polarization relative to the first pair of bulk acoustic wave resonators; and
a capacitor connected to a common electrode of the first bulk acoustic wave resonator and the second bulk acoustic wave resonator, the capacitor configured to compensate for a mismatch in parasitic capacitance between the first pair of bulk acoustic wave resonators and the second pair of bulk acoustic wave resonators, the acoustic wave filter configured to filter a radio frequency signal, and the acoustic wave filter is included in a multiplexer that includes at least one additional acoustic wave filter connected to the acoustic wave filter at a common node.
2 . The acoustic wave filter of claim 1 further comprising a plurality of additional acoustic wave resonators.
3 . The acoustic wave filter of claim 2 wherein all other acoustic wave resonators of the acoustic wave filter are coupled to an antenna node by way of the first and second pairs of bulk acoustic wave resonators.
4 . The acoustic wave filter of claim 2 wherein the plurality of additional acoustic wave resonators includes a pair of shunt resonators in anti-parallel with each other in a filter stage.
5 . An acoustic wave filter with second harmonic emission suppression, the acoustic wave filter comprising:
a first pair of bulk acoustic wave resonators in anti-series with each other, the first pair of bulk acoustic wave resonators including a first bulk acoustic wave resonator and a second bulk acoustic wave resonator;
a second pair of bulk acoustic wave resonators in anti-series with each other, the second pair of bulk acoustic wave resonators being in parallel with the first pair of bulk acoustic wave resonators, and the second pair of bulk acoustic wave resonators having reverse electrode polarization relative to the first pair of bulk acoustic wave resonators;
a plurality of additional acoustic wave resonators that includes a pair of series bulk acoustic wave resonators in anti-series with each other in a filter stage; and
a capacitor connected to a common electrode of the first bulk acoustic wave resonator and the second bulk acoustic wave resonator, the capacitor configured to compensate for a mismatch in parasitic capacitance between the first pair of bulk acoustic wave resonators and the second pair of bulk acoustic wave resonators, the acoustic wave filter configured to filter a radio frequency signal.
6 . The acoustic wave filter of claim 5 further comprising a second capacitor connected to a common electrode of the pair of series bulk acoustic wave resonators.
7 . The acoustic wave filter of claim 2 wherein the plurality of additional acoustic wave resonators are bulk acoustic wave resonators.
8 . The acoustic wave filter of claim 1 wherein the first and second bulk acoustic wave resonators are series bulk acoustic wave resonators.
9 . The acoustic wave filter of claim 1 wherein the acoustic wave filter is a transmit filter.
10 . The acoustic wave filter of claim 5 wherein the acoustic wave filter is included in a multiplexer that includes at least one additional acoustic wave filter connected to the acoustic wave filter at a common node.
11 . The acoustic wave filter of claim 1 wherein the capacitor has a capacitance in a range from 0.03 picofarad to 0.2 picofarad.
12 . An acoustic wave filter with second harmonic emission suppression, the acoustic wave filter comprising:
a first pair of bulk acoustic wave resonators in anti-series with each other, the first pair of bulk acoustic wave resonators including a first bulk acoustic wave resonator and a second bulk acoustic wave resonator;
a second pair of bulk acoustic wave resonators in anti-series with each other, the second pair of bulk acoustic wave resonators being in parallel with the first pair of bulk acoustic wave resonators, and the second pair of bulk acoustic wave resonators having reverse electrode polarization relative to the first pair of bulk acoustic wave resonators; and
a capacitor connected to a common electrode of the first bulk acoustic wave resonator and the second bulk acoustic wave resonator, the capacitor configured to compensate for a mismatch in parasitic capacitance between the first pair of bulk acoustic wave resonators and the second pair of bulk acoustic wave resonators, the acoustic wave filter configured to filter a radio frequency signal, and the capacitor includes at least one of an interdigital transducer electrode capacitor, a resonator capacitor, a near metal capacitor, or a metal-insulator-metal capacitor.
13 . The acoustic wave filter of claim 1 wherein the capacitor is a resonator capacitor.
14 . The acoustic wave filter of claim 1 wherein the capacitor is a near metal capacitor.
15 . The acoustic wave filter of claim 1 wherein the capacitor is a metal-insulator-metal capacitor.
16 . An acoustic wave filter with second harmonic emission suppression, the acoustic wave filter comprising:
a first pair of bulk acoustic wave resonators in anti-series with each other, the first pair of bulk acoustic wave resonators including a first bulk acoustic wave resonator and a second bulk acoustic wave resonator;
a second pair of bulk acoustic wave resonators in anti-series with each other, the second pair of bulk acoustic wave resonators being in parallel with the first pair of bulk acoustic wave resonators, and the second pair of bulk acoustic wave resonators having reverse electrode polarization relative to the first pair of bulk acoustic wave resonators;
a pair of shunt bulk acoustic wave resonators in anti-series with each other and a second capacitor connected to a common electrode of the pair of shunt bulk acoustic wave resonators; and
a capacitor connected to a common electrode of the first bulk acoustic wave resonator and the second bulk acoustic wave resonator, the capacitor configured to compensate for a mismatch in parasitic capacitance between the first pair of bulk acoustic wave resonators and the second pair of bulk acoustic wave resonators, the acoustic wave filter configured to filter a radio frequency signal.
17 . A radio frequency module comprising:
an acoustic wave filter including a first pair of bulk acoustic wave resonators in anti-series with each other, a second pair of bulk acoustic wave resonators in anti-series with each other and having reverse electrode polarization relative to the first pair of bulk acoustic wave resonators, and a capacitor connected to a common electrode of a first bulk acoustic wave resonator and a second bulk acoustic wave resonator of the first pair of bulk acoustic wave resonators;
radio frequency circuitry coupled to the acoustic wave filter; and
a package structure enclosing the acoustic wave filter and the radio frequency circuitry.
18 . The radio frequency module of claim 17 wherein the radio frequency circuitry includes a switch and a power amplifier.
19 . The radio frequency module of claim 17 wherein the acoustic wave filter is included in a multiplexer, the multiplexer including a second filter connected to the acoustic wave filter at a common node.
20 . A method of radio frequency signal processing with second harmonic emission suppression, the method comprising:
amplifying a radio frequency signal; and
filtering the radio frequency signal with the acoustic wave filter of claim 1 .