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.

An LC circuit includes a first capacitor provided between a first connection point and a second connection point, a second capacitor provided between the second connection point and a third connection point, a third capacitor provided between the third connection point and a fourth connection point, a fourth capacitor provided between the first connection point and the third connection point, a fifth capacitor provided between the second connection point and the fourth connection point, a first inductor connected to the second connection point, and a second inductor connected to the third connection point.

A band-pass filter includes an unbalanced port, a first balanced port, a second balanced port, and first to third resonators provided between the unbalanced port and the first and second balanced ports. The second resonator and the third resonator each are a resonator with both ends open. The second resonator and the third resonator are adjacent to each other in a circuit configuration, and electromagnetically coupled by magnetic coupling as main coupling. The first resonator is provided closer to the second resonator than to the third resonator, and jump-coupled to the third resonator.

A method includes converting, by n analog to digital converter circuits, n analog signals into n first digital signals having a first data rate frequency; converting, by n digital decimation filtering circuits, the n first digital signals into n second digital signals having a second data rate frequency; and converting, by n digital bandpass filter (BPF) circuits, the n second digital signals into a plurality of outbound digital signals having a third data rate frequency. The coefficients for the taps of a digital BPF circuit is set to produce a bandpass region approximately centered at the oscillation frequency of the analog signal and having a bandwidth tuned for filtering a pure tone component of the analog signal. The first data rate frequency is a first integer multiple of the third data rate frequency. The second data rate frequency is a second integer multiple of the third data rate frequency.

A band-pass filter includes an unbalanced port, a first balanced port, a second balanced port, and first to third resonators provided between the unbalanced port and the first and second balanced ports. The second resonator and the third resonator each are a resonator with both ends open. The second resonator and the third resonator are adjacent to each other in a circuit configuration, and electromagnetically coupled by magnetic coupling as main coupling. The first resonator is provided closer to the second resonator than to the third resonator, and jump-coupled to the third resonator.

A band pass filter includes filter circuits, first and second intermediate circuits, and a first capacitor. The first intermediate circuit includes an inductor connected between second and third capacitors. The second intermediate circuit includes an inductor connected between third and fourth capacitors. Resonant circuits included in the filter circuit are connected to ground via a common capacitor. Resonant circuits included in the filter circuit are connected to the ground via a common capacitor. The first capacitor is connected between the first and second intermediate circuits.

A radio frequency (RF) filter circuit for rejecting one or more spurious components of an input signal has a first resonator circuit including a first capacitor and a first coupled inductor pair of a first inductor and a second inductor, and a second resonator circuit with a second capacitor and a second coupled inductor pair of a third inductor and a fourth inductor. First and second resonator coupling capacitors are connected to the first resonator circuit and the second resonator circuit. A first port and a second port are connected to the first resonator circuit and the second resonator, with the filtered signal of the input signal passed through both the first resonator circuit and the second resonator circuit being output.

The present disclosure describes a method and arrangement for damping a resonant component of a common-mode current of a multi-phase power converter comprising an output filter with a virtual ground connection to the power converter. In the method and arrangement, the common-mode current is determined, a feedback signal is formed on the basis of the common-mode current, and the feedback signal is injected into a common mode current reference in order to dampen the resonance frequency component. A delay is added to the feedback signal so that the feedback signal has a sufficient phase margin with respect to a subsequent cycle of the resonance frequency component of the common-mode current.

A filter device includes a dielectric substrate, first and second ground electrodes connected to a ground terminal, and resonators between the ground electrodes and electromagnetically coupled to each other. The ground electrodes are at different positions in a normal direction of the dielectric substrate. Each of the resonators includes a first capacitor electrode partially overlapping with the first ground electrode in plan view of the dielectric substrate, a second capacitor electrode partially overlapping with the second ground electrode in plan view of the dielectric substrate, and a via connecting the capacitor electrodes. The resonators include a first resonator connected to an input terminal, a second resonator connected to an output terminal, and a third resonator between the first and second resonators. Shunt electrodes are connected to the via and the ground terminal in the first and second resonators, respectively.

A filter device includes a body, a ground terminal, and resonators in the body and coupled to each other by electromagnetic field coupling. The resonators include a first resonator coupled to an input terminal, a second resonator coupled to an output terminal, and third and fourth resonators. The second resonator is adjacent to the first resonator in a first direction. The third resonator is adjacent to the first resonator in a second direction perpendicular to the first direction. The fourth resonator is adjacent to the third resonator in the first direction. The third and fourth resonators partially share a path to the ground terminal.