Embodiments of resonator circuits and modulating resonators and are described generally herein. One or more acoustic wave resonators may be coupled in series or parallel to generate tunable filters. One or more acoustic wave resonances may be modulated by one or more capacitors or tunable capacitors. One or more acoustic wave modules may also be switchable in a filter. Other embodiments may be described and claimed.

Embodiments of a method and an apparatus for a quadrature hybrid are disclosed. In an embodiment, a quadrature hybrid includes a first port, a second port, a third port, a fourth port, first, second, and third inductors, first, second, third, and fourth capacitors, and a first variable capacitor tuning network connected between the first port and the fourth port, and a second variable capacitor tuning network connected between the second port and the third port.

Radio-frequency splitter circuits, devices and methods. In some embodiments, a power splitter can include an input port, a first output port and a second output port. The power splitter can further include a first signal path implemented between the input port and the first output port, and a second signal path implemented between the input port and the second output port. Each of the first and second signal paths can include a variable capacitance configured to provide a plurality of capacitance values that result in different frequency responses of the respective signal path.

A wide-bandwidth resonant circuit is provided. In an embodiment disclosed herein, the wide-bandwidth resonant circuit includes a positive resonant circuit coupled in parallel to a negative resonant circuit. The positive resonant circuit and the negative resonant circuit can be configured to collectively exhibit certain impedance characteristics across a wide bandwidth. As a result, it is possible to utilize the wide-bandwidth resonant circuit to support a variety of wide-bandwidth applications, such as in a wide-bandwidth signal filter circuit.

Reducing harmonics in a radio transmitter can involve using an electronically tunable harmonic filter (ETHF) in a transmit path at the output of an RF power amplifier stage to reduce harmonic signal components in the RF transmit signal. At least one filter characteristic of the ETHF is selectively controlled using one or more RF switch. The one or more RF switches that are used to control the ETHF can include a CMOS-SOI and/or a MEMs type of switch. Various filter characteristics of the ETHF can be controlled including a bandwidth and/or a center frequency of the ETHF.

Disclosed is a gallium arsenide (GaAs) enabled tunable filter for, e.g., 6 GHz Wi-Fi RF Frontend, with integrated high-performance varactors, metal-insulator-metal (MIM) capacitors, and 3D solenoid inductors. The tunable filter comprises a hyper-abrupt variable capacitor (varactor) high capacitance tuning ratio. The tunable filter also comprises a GaAs substrate in which through-GaAs-vias (TGV) are formed. The varactor along with the MIM capacitors and the 3D inductors is formed in an upper conductive structure on upper surface of the GaAs substrate. Lower conductive structure comprising lower conductors is formed on lower surface of the GaAs substrate. Electrical coupling between the lower and upper conductive structures is provided by the TGVs. The tunable filter can be integrated with radio frequency front end (RFFE) devices.

Embodiments of resonator circuits and modulating resonators and are described generally herein. One or more acoustic wave resonators may be coupled in series or parallel to generate tunable filters. One or more acoustic wave resonances may be modulated by one or more capacitors or tunable capacitors. One or more acoustic wave modules may also be switchable in a filter. Other embodiments may be described and claimed.

A system includes a control circuit and an adjustable low-pass filter. The control circuit is configured to receive an input signal and to control at least one engine output based on the input signal. The adjustable low-pass filter receives the input signal, and filters the input signal prior to forwarding the input signal to the control circuit. The adjustable low-pass filter has a first setting in which the adjustable low-pass filter has a first cut-off frequency and a second setting in which the adjustable low-pass filter has a second cut-off frequency. The first setting configures the control circuit to be used with a first sensor having a first dynamic range and the second setting configures the control circuit to be used with a second sensor having a second dynamic range.

A radio-frequency module is provided that includes a structure, a filtering element disposed on the structure, a switching element embedded in the structure, and an impedance element connected to the switching element and the filtering element. In a plan view of the structure, the switching element and the filtering element overlap each other in at least part thereof. The structure has a plurality of vias including a via , a via and a via. The via connects the input-output terminal and the filtering element. The via connects the ground terminal and an impedance adjustment circuit including the switching element and the impedance element. In a plan view, the via is located in a smallest rectangular region encompassing the vias.

A time constant calibration circuit and method. The circuit comprises a resistor, a capacitor, an amplifier, a first switch and a second switch. The resistance of the resistor and/or the capacitance of the capacitor is variable. A first terminal of the resistor, a first terminal of the capacitor and a first input of the amplifier are coupled to a common node, which is coupleable to a reference current source. A second input of the amplifier is coupleable to a reference voltage. An output of the amplifier is coupled to a second terminal of the resistor and a second terminal of the capacitor. The circuit can perform a calibration process comprising one or more calibration cycles in which the switches route a reference current through the resistor in a first phase and through the capacitor in a second phase. The resistance and/or the capacitance is adjusted between calibration cycles.