A filter circuit comprises a main operating unit (MU) arranged in the series signal line providing most of the filter function of the filter circuit. A micro acoustic last series resonator (RL.sub.s) as a last element of the main operating unit in the series signal line is prone to excite a spurious mode that is damped with a final series capacitance (CE.sub.s) circuited between the last element and the antenna terminal (AT).

A multiplexer includes a common terminal, reception output terminals (120 and 130), a filter (20) that is connected between the common terminal and the reception output terminal (120), a filter (30) that is connected between the common terminal and the reception output terminal (130) and has a pass band different from a pass band of the filter (20), and an impedance matching circuit that is arranged between the common terminal and the filter (30). The impedance matching circuit includes a parallel-arm resonator that is connected between a node (N1) on a path connecting the common terminal to the filter (30) and a ground.

Examples of a capacitive-coupled bandpass filter include a plurality of coupling capacitors connected in series along a signal path extending between an input contact and an output contact, a first harmonic suppression notch circuit configured to provide a first harmonic suppression notch in a frequency response of the capacitive-coupled bandpass filter, and a second harmonic suppression notch circuit configured to provide a second harmonic suppression notch in the frequency response of the capacitive-coupled bandpass filter. The first harmonic suppression notch circuit includes a first pair of series L/C resonators connected in shunt between the signal path and a reference potential, and the second harmonic suppression notch circuit includes a second pair of series L/C resonators connected in shunt between the signal path and the reference potential.

Apparatus and methods for control and calibration of tunable filters are provided. In certain embodiments, a tunable filter includes at least one controllable component (for instance, a controllable inductor or a controllable capacitor) having a value that changes or adjusts a center frequency of the tunable filter. For example, the controllable component can correspond to a controllable inductor or a controllable capacitor of an inductor-capacitor (LC) resonator of the tunable filter. The tunable filter further includes a control circuit implemented with an approximation function for estimating a value of the controllable component for achieving a desired center frequency indicated by a frequency control signal.

An impedance matching device 2A connected between one or more plasma generating electrodes 51, 52 and a RF power supply 1 that selectively supplies RF power of multiple frequencies includes multiple matching devices 31, 32 each of which corresponds to each frequency of the multiple frequencies of the RF power, and matches an impedance of the RF power supply 1 to an impedance of a plasma load, and a demultiplexer 20 that demultiplexes the RF power of multiple frequencies output by the RF power supply 1 and feeds each of the demultiplexed RF power to a corresponding matching device in the multiple matching devices 31, 32.

Embodiments disclosed herein relate to isolating a receiver circuit of an electronic device from a transmission signal and leakage of the transmission signal. To do so, an isolation circuit is disposed between the receiver circuit and a transmission circuit. The isolation circuit may include multiple variable impedance devices and one or more antennas. The impedances of the variable impedance devices may be balanced such that a signal at a particular frequency or within a particular frequency band can pass through or is blocked by the isolation circuit. The isolation circuit may include one or more double balanced duplexers to achieve the improved isolation. The isolation circuit may also increase bandwidth available for wireless communications of the electronic device.

Systems, methods, and devices for reducing insertion loss and/or swapping transmitter (TX) and receiver (RX) frequencies in an electrical balance duplexer (EBD) used in a transceiver device for frequency division duplexing (FDD) applications are provided. Feed-forward receiver path from the antenna to a low noise amplifier (LNA) and a feed-forward path from the antenna to a power amplifier (PA) of the EBD may be used for reducing insertion loss of the RX and TX signals. In some embodiments, switches may be used to selectively alter operational modes for varied levels of isolation and/or swapping of TX and RX frequencies.

A multiplexer includes: a multilayered body including dielectric layers stacked and having first and second surfaces; a common terminal, a first terminal, a second terminal, and a ground terminal disposed on a surface of the multilayered body; a first filter disposed in the multilayered body and electrically connected between the common terminal and the first terminal; a second filter including: a first inductor electrically connected between the common terminal and the second terminal; and a second inductor connected in series with the first inductor between the first inductor and the second terminal, the second inductor at least partially overlapping with the first inductor, a capacitance between a first end of the second inductor electrically closer to the common terminal and the ground terminal being larger than a capacitance between a first end of the first inductor electrically closer to the common terminal and the ground terminal.

An apparatus is disclosed with an absorptive filter. In an example aspect, an apparatus has a filter including a first filter port and a second filter port. The filter also includes a hybrid coupler, a signal combiner, a first filter unit, and a second filter unit. The hybrid coupler includes a first hybrid port, a second hybrid port, and a third hybrid port, with the first hybrid port coupled to the first filter port. The signal combiner is coupled to the second filter port. The first filter unit is coupled between the second hybrid port and the signal combiner. The second filter unit is coupled between the third hybrid port and the signal combiner.

Disclosed are devices and methods for fabricating devices. A device can include a passive portion having at least one metal insulator metal (MIM) capacitor and at least one 2-dimensional (2D) inductor. The device further includes a substrate and the passive portion is formed on the substrate. A magnetic core is embedded in the substrate. A 3-dimensional (3D) inductor is also included having windings formed at least in part in the substrate and at least a portion of the windings being formed around the magnetic core.