An acoustic wave device includes a piezoelectric body made of lithium niobate and disposed directly or indirectly on a supporting substrate, and IDT electrode disposed directly or indirectly on the piezoelectric body. When the wavelength of an acoustic wave that is determined by a pitch of electrode fingers of the IDT electrode is denoted by λ, the thickness of the piezoelectric body is equal to or less than about 1λ. The acoustic wave device uses the plate wave S0 mode propagating in the piezoelectric body. The Euler angles of the lithium niobate are (0°±10°, θ, 90°±10°), provided that θ is from about 0° to about 180° inclusive.

Radio frequency (RF) systems with tunable filters are provided herein. In certain embodiments, an RF system includes a first RF processing circuit configured to process a first frequency band of a first communication standard and a second frequency band of a second communication standard. The first frequency band and the second frequency band are close in frequency and/or partially overlapping in frequency. The first RF processing circuit includes a tunable filter for changing the bandwidth of the first RF processing circuit to enhance the robustness of the first RF processing circuit to blocker or jammer signals of a third frequency band.

An analog to digital conversion circuit includes an analog to digital converter (ADC) circuit operable to convert an analog signal having an oscillation frequency into a first digital signal having a first data rate frequency. The analog signal includes a set of pure tone components. The first digital signal includes n 1-bit channels. The analog to digital conversion circuit further includes a digital decimation filtering circuit including n anti-aliasing filters operable to sample and filter the n 1-bit channels of the first digital signal to produce n second digital signals and n decimator circuits operable to decimate the n second digital signals to produce n third digital signals at a second data rate frequency. The analog to digital conversion circuit further includes a multiplexor operable to output the n third digital signals at the second data rate frequency on a single bus.

A bandpass filter circuit includes a fourth element that is a capacitor having one end connected to a first node, a fifth element that is a capacitor having one end connected to a second node, a sixth element that is a capacitor connected between other end of the fourth element and other end of the fifth element, a seventh element that is an inductor having one end connected to a fourth node to which the fourth element and the sixth element are connected, other end of the seventh element is connected to a ground terminal, and an eighth element that is an inductor having one end connected to a fifth node to which the fifth element and the sixth element are connected, other end of the eighth element is connected to the ground terminal.

Disclosed is a radio frequency (RF) filter that vertically integrates an acoustic wave filter with an integrated passive device (IPD) filter. The acoustic wave filter provides selectivity at fundamental frequency band while the IPD filter provides rejection at harmonic frequency bands.

The, present application provides a filtering circuit and a. TV antenna amplifier, the filtering circuit includes a switching module, and the switching module includes a control unit and at least two filtering units. The present application switchably render one of the at least two filtering units conductive through the control unit, and filter the signals of different frequencies in the input signals through the at least two filtering units, so that different filtering units can be switched according to the filtering requirements of the frequency signal in different regions, which makes it a wide application range.

An acoustic device includes a foundation structure and a transducer provided over the foundation structure. The foundation structure includes a piezoelectric layer between a top electrode and a bottom electrode. The piezoelectric layer has an active portion within an active region of the transducer, and a bi-polar border portion within a border region of the transducer. The piezoelectric material in the active portion has a first polarization. The bi-polar border portion has a first sub-portion and a second sub-portion, which resides either above or below the first sub-portion. The piezoelectric material in the first sub-portion has the first polarization, and the piezoelectric material in the second sub-portion has a second polarization, which is opposite the first polarization.

A multilayer filter may include a signal path having an input, an output, and a conductive layer overlying at least one of a plurality of dielectric layers. The conductive layer may be elongated in the first direction and may have a first edge aligned with the first direction and a second edge parallel with the first edge. The conductive layer may include a protrusion extending in the second direction and having an end edge that is parallel with the first edge and offset from the first edge in the second direction by a protrusion length that is greater than about 50 microns. The multilayer filter may include an inductor that is electrically connected at a first location with the signal path and electrically connected at a second location with at least one of the signal path or a ground.

A frontend module includes a first filter having a passband of a first frequency band, a second filter having a passband of a second frequency band, the second frequency band being higher than the first frequency band, a third filter having a passband of a third frequency band, the third frequency band being higher than the second frequency band, and a sub-filter, connected to the second filter, configured to provide attenuation characteristics for the first frequency band, wherein the second filter comprises a plurality of parallel LC resonance circuits arranged between a ground and different nodes, from among a plurality of nodes between a first terminal and a second terminal, wherein an inductor is connected to a portion of the plurality of parallel LC resonance circuits.

Described is a bandpass filter comprising a multi-layered body, a first resonator conductor formed on a first layer of the body and a second resonator conductor formed on a second, tower layer of the body. The first resonator conductor and the second resonator conductor comprise a first coupling area formed by only a partial overlap of the first resonator conductor and the second resonator conductor. A length of each said resonator conductor is in the range of λ.sub.g/3 to λ.sub.g/5, where λ.sub.g. is a center wavelength of the bandpass filter passband.