Nonlinear acoustic media and related methods are described herein. The nonlinear acoustic media are configured to generate higher harmonic output signals from a single-frequency input signal. The higher harmonic output signals can be generated through the coupling of an acoustic dielectric medium to a nonlinear piezoelectric medium having four ports.

The present disclosure relates to a Bulk Acoustic Wave (BAW) resonator with tunable electromechanical coupling. The disclosed BAW resonator includes a bottom electrode, a top electrode, and a multilayer transduction structure sandwiched therebetween. Herein, the multilayer transduction structure is composed of multiple transduction layers, and at least one of the transduction layers is formed of a ferroelectric material, whose polarization will vary with an electric field across the ferroelectric material. Upon adjusting direct current (DC) bias voltage across the bottom electrode and the top electrode, an overall polarization of the multilayer transduction structure and an overall electromechanical coupling coefficient of the multilayer transduction structure are capable of being changed. Once the change of the overall electromechanical coupling coefficient of the multilayer transduction structure is completed, the overall electromechanical coupling coefficient of the multilayer transduction structure will remain unchanged after removing the DC bias voltage.

The present disclosure relates to a Bulk Acoustic Wave (BAW) resonator with tunable electromechanical coupling. The disclosed BAW resonator includes a bottom electrode, a top electrode, and a multilayer transduction structure sandwiched therebetween. Herein, the multilayer transduction structure is composed of multiple transduction layers, and at least one of the transduction layers is formed of a ferroelectric material, whose polarization will vary with an electric field across the ferroelectric material. Upon adjusting direct current (DC) bias voltage across the bottom electrode and the top electrode, an overall polarization of the multilayer transduction structure and an overall electromechanical coupling coefficient of the multilayer transduction structure are capable of being changed. Once the change of the overall electromechanical coupling coefficient of the multilayer transduction structure is completed, the overall electromechanical coupling coefficient of the multilayer transduction structure will remain unchanged after removing the DC bias voltage.

A power noise filter and a supply modulator including the same, and a wireless communication device including the power noise filter are provided. The power noise filter includes a band stop filter and a low pass filter. The band stop filter includes an inductor and a first capacitor, which are connected in parallel between first and second nodes. The first node receives a first voltage, which is filtered by the band pass filter to thereby generate a second voltage at the second node. The first low pass filter includes the inductor and a second capacitor, which has one end connected to the second node and an opposite end connected to a ground source.

A power noise filter and a supply modulator including the same, and a wireless communication device including the power noise filter are provided. The power noise filter includes a band stop filter and a low pass filter. The band stop filter includes an inductor and a first capacitor, which are connected in parallel between first and second nodes. The first node receives a first voltage, which is filtered by the band pass filter to thereby generate a second voltage at the second node. The first low pass filter includes the inductor and a second capacitor, which has one end connected to the second node and an opposite end connected to a ground source.

An acoustic wave filter device with two-stage acoustic wave filters is provided. Each of the two stages includes a respective acoustic wave filter element. A first acoustic wave filter element (100a) includes a first input electrode (150a), a first output electrode (174a), and a first counter electrode (120a). The first input electrode and the first output electrode are located on a top surface of piezoelectric layer (650), and the first counter electrode is located on a bottom surface of the piezoelectric layer. A second acoustic wave filter element (100b) includes a second input electrode (154b), a second output electrode (174b), and a second counter electrode (120b). The second input electrode and the second output electrode are located on the top surface of the piezoelectric layer, and the second counter electrode is located on a bottom surface of the piezoelectric layer. The two acoustic wave filter elements are connected in series through a common floating electrode (602).

An acoustic wave filter device with two-stage acoustic wave filters is provided. Each of the two stages includes a respective acoustic wave filter element. A first acoustic wave filter element (100a) includes a first input electrode (150a), a first output electrode (174a), and a first counter electrode (120a). The first input electrode and the first output electrode are located on a top surface of piezoelectric layer (650), and the first counter electrode is located on a bottom surface of the piezoelectric layer. A second acoustic wave filter element (100b) includes a second input electrode (154b), a second output electrode (174b), and a second counter electrode (120b). The second input electrode and the second output electrode are located on the top surface of the piezoelectric layer, and the second counter electrode is located on a bottom surface of the piezoelectric layer. The two acoustic wave filter elements are connected in series through a common floating electrode (602).

There are disclosed radio frequency multiplexers and methods of designing radio frequency multiplexers. A radio frequency multiplexer includes three or more band-pass filters having respective passbands, each band-pass filter comprising two or more acoustic resonators. A first end of each of the three or more band-pass filters is connected to a respective branch port. A second end of each of the three or more band-pass filters is connected to a common node without an intervening phasing network. A shunt reactive element connected between the common node and ground.

There are disclosed radio frequency multiplexers and methods of designing radio frequency multiplexers. A radio frequency multiplexer includes three or more band-pass filters having respective passbands, each band-pass filter comprising two or more acoustic resonators. A first end of each of the three or more band-pass filters is connected to a respective branch port. A second end of each of the three or more band-pass filters is connected to a common node without an intervening phasing network. A shunt reactive element connected between the common node and ground.

In accordance with an embodiment, an RF system includes a transmit path having a first tunable transmit band stop filter, and a power amplifier coupled to an output of the first tunable transmit band stop filter, where the first tunable transmit band stop filter is configured reject a receive frequency and pass a transmit frequency; a receive path comprising an LNA; and a duplex filter having a transmit path port coupled to an output of the power amplifier, a receive path port coupled to an input of the LNA, and an antenna port, where the duplex filter is configured to pass the transmit frequency and reject the receive frequency between the antenna port and the transmit path port, pass the receive frequency and reject the transmit frequency between the antenna port and the receive path port.