An electrically tunable radio frequency phase shifter with compact 3-D structure that integrates both ferromagnetic and ferroelectric materials, and utilizes 3-D structure to increase the tuning efficiency and achieve miniaturization.

Systems, devices, and methods for tunable filters that are configured to support multiple frequency bands, such as within the field of cellular radio communication, can include a first resonator and a second resonator configured to block signals within one or more frequency ranges, and one or more coupling element connected to both the first resonator and the second resonator. The one or more coupling element can be configured to provide low insertion loss within a pass band.

Aspects of this disclosure relate to a radio frequency system with tunable notch filtering. The radio frequency system includes a first tunable filter and a second tunable filter. The first tunable filter is coupled between an output of a power amplifier and a radio frequency switch. The second tunable filter is coupled between an antenna switch and an antenna node. The second tunable filter has a notch at a lower frequency than a notch of the first tunable filter. Related methods and wireless communication devices are also disclosed.

A method that incorporates teachings of the subject disclosure may include, for example, a method comprising receiving from a transceiver that is implemented as an integrated circuit (IC) chip, by a variable reactive element, a signal, wherein the signal is in a frequency band that comprises a first sub-frequency band and a second sub-frequency band, controlling, by a controller, the variable reactive element, such that the variable reactive element is placed into one of a group of states, wherein the group of states comprises a first state having a first reactance and a second state having a second reactance, and wherein the first reactance is different from the second reactance. Other embodiments are disclosed.

A phase actuator for a continuously adjustable phase displacement at a first frequency is provided. The phase actuator has a first inductance with tapping point, a first continuously variable capacitor, and a transformation network. A signal input and a signal output of the phase shifter are connected by the first inductance. The first continuously adjustable capacitor is connected in parallel to the first inductance. The tapping point is connected via a transformation network to a reference mass, where an impedance value of the transformation network corresponds to a quarter wave transform of a capacitance value of the first continuously variable capacitance at the first frequency.

A flexible multi-path RF adaptive tuning network switch architecture that counteracts impedance mismatch conditions arising from various combinations of coupled RF band filters, particularly in a Carrier Aggregation-based (CA) radio system. In one version, a digitally-controlled tunable matching network is coupled to a multi-path RF switch in order to provide adaptive impedance matching for various combinations of RF band filters. Optionally, some or all RF band filters include an associated digitally-controlled filter pre-match network to further improve impedance matching. In a second version, some or all RF band filters coupled to a multi-path RF switch include a digitally-controlled phase matching network to provide necessary per-band impedance matching. Optionally, a digitally-controlled tunable matching network may be included on the common port of the multi-path RF switch to provide additional impedance matching capability. In a third version, CA direct mapped adaptive tuning networks include filter tuning blocks for selected lower frequency bands.

A tunable filter using acoustic resonators is disclosed. A tunable filter includes a plurality of tunable resonator units (20). Each tunable resonator unit (20) has acoustic wave resonators (12). Each acoustic wave resonator is associated with a different tunable frequency. Each tunable resonator unit also has a first switch (22) configured to select one of the plurality of acoustic wave resonators of the tunable resonator unit at a time. The first switches of the plurality of tunable resonator units are coupled to cooperatively select one acoustic wave resonator in each one of the plurality of tunable resonator units, where a selected acoustic wave resonator in a tunable resonator unit of the plurality of tunable acoustic resonator units is associated with a same tunable frequency response as the other selected acoustic resonators of the others of the plurality of tunable acoustic resonator units. The selection results in an overall tunable frequency response.

A capacitor having a capacitance settable by biasing, including: a series association of a plurality of first capacitive elements between two first terminals defining the capacitor electrodes; and two second terminals of application of bias voltages respectively connected, via resistive elements, to the opposite electrodes of each of the first capacitive elements.

Aspects of this disclosure relate to a radio frequency system with tunable notch filtering. The radio frequency system includes a first tunable filter and a second tunable filter. The first tunable filter is coupled between an output of a power amplifier and a radio frequency switch. The second tunable filter is coupled between an antenna switch and an antenna node. The second tunable filter has a notch at a lower frequency than a notch of the first tunable filter. Related methods and wireless communication devices are also disclosed.

A tunable filter includes a series-arm resonant circuit, and a parallel-arm resonant circuit. The series-arm resonant circuit includes a group of acoustic wave resonant circuits that have different resonant frequencies, a variable capacitor, and switching circuits. The parallel-arm resonant circuit includes another group of acoustic wave resonant circuits that have different resonant frequencies, a variable capacitor, and switching circuits. For example, the difference in pass-band frequency caused by the difference in resonant frequency between the acoustic wave resonant circuit in the group and the acoustic wave resonant circuit in the other group is greater than the maximum difference in pass-band frequency resulting from the variable range of capacitance of the variable capacitor.