Acoustic resonator filter

An acoustic resonator filter comprising:

• at least one series acoustic resonator electrically connected between a first port and a second port in series, and configured to pass a radio frequency (RF) signal;
• at least one second shunt acoustic resonator electrically shunt-connected between the at least one series acoustic resonator and a ground;
• and
• at least one first shunt acoustic resonator electrically shunt-connected between the at least one series acoustic resonator and the ground and having a resonance frequency higher than a resonance frequency of the at least one second shunt acoustic resonator,
• wherein each of the at least one first shunt acoustic resonator, the at least one second shunt acoustic resonator, and the at least one series acoustic resonator comprise a first electrode and a second electrode, spaced apart from each other, respectively;
• and
• a piezoelectric layer disposed between the respective first and second electrodes,
• wherein at least one shunt acoustic resonator, among the at least one first shunt acoustic resonator and the at least one second shunt acoustic resonator, comprises a SiO2 layer disposed between the first and second electrodes or disposed to contact one of the first and second electrodes, and
• wherein the at least one series acoustic resonator does not include a SiO2 layer or includes a SiO2 layer smaller than the SiO2 layer of the at least one shunt acoustic resonator.

An acoustic resonator filter comprising:

• at least one series acoustic resonator electrically connected between a first port and a second port in series, and configured to pass a radio frequency (RF) signal;
• at least one second shunt acoustic resonator electrically shunt-connected between the at least one series acoustic resonator and a ground;
• and
• at least one first shunt acoustic resonator electrically shunt-connected between the at least one series acoustic resonator and the ground and having a resonance frequency higher than a resonance frequency of the at least one second shunt acoustic resonator,
• wherein at least one shunt acoustic resonator, among the at least one first shunt acoustic resonator and the at least one second shunt acoustic resonator, has a temperature coefficient of frequency (TCF) corresponding to resonance frequency sensitivity more insensitive than resonance frequency sensitivity according to a change in temperature of the at least one series acoustic resonator filter, and
• wherein a difference between a bandwidth at −40 degrees Celsius and a bandwidth at +95 degrees Celsius is less than 20 MHz.