A network interface device includes an active path between an entry port and a first input/output port. The network interface device also includes a passive path between the entry port and a second input/output port. The network interface device also includes a buffer in the active path configured to absorb, attenuate, terminate, or isolate radio-frequency (RF) signals. The network interface device also includes a switching element in the active path configured to selectively bypass the buffer during normal operating conditions.

A filter includes a series arm circuit connected between an input-output terminal and an input-output terminal and a parallel arm circuit connected between a ground and a node. The parallel arm circuit includes a first circuit and a second circuit. The first circuit has a parallel arm resonator. The second circuit is connected in parallel with the first circuit and has a parallel arm resonator. At least one of the first and second circuits includes a variable frequency circuit. The variable frequency circuit is connected in series with the parallel arm resonator or the parallel arm resonator included in the corresponding one of the first and second circuits. The variable frequency circuit has an impedance element and a switch connected in parallel with each other. The parallel arm resonator has a resonant frequency different from the parallel arm resonator and an anti-resonant frequency different from the parallel arm resonator.

A first attenuation circuit is connected between a node and ground, and the node is located between a ladder resonance circuit and a transmitter-side terminal. A second attenuation circuit is connected between a first parallel arm resonator of the ladder resonance circuit and ground and is connected in series to the first parallel arm resonator. The first attenuation circuit includes a second parallel arm resonator and a first switch that switches between a first state in which the second parallel arm resonator is connected to the node and a second state in which the first switch is open. The second attenuation circuit includes a capacitor and a second switch that switches between a first state in which the capacitor is connected to the first parallel arm resonator and a second state in which the first parallel arm resonator is connected to ground.

An antenna system includes N integrated passive components (IPCs). A first end of each IPC of the N IPCs is directly configured to couple to an antenna for receiving signals of a band corresponding to the IPC and filtering signals of bands corresponding to other IPCs of the N IPCs. The antenna system can prevent signals of various bands from interfering with each other, reduces parasitic capacitance effect, and further improves nonlinear distortion.

A multiplexer includes a first filter, a second filter, a combining wiring line that provides a combination point at which an input or an output of each of the first filter and the second filter is connected to each other, an antenna terminal to connect the multiplexer to an antenna, an antenna wiring line connected at one end to the antenna terminal and connected at the other end to the combining wiring line, a matching terminal to which a matching inductor to provide matching between the antenna and the multiplexer is to be connected, and a matching wiring line to be connected at one end to the matching terminal and connected at the other end to the combining wiring line.

The cut-off frequency of an electronic filter having a nominal transfer function and a nominal cut-off frequency is estimated by: applying a first signal at a first frequency to an input of the filter while sampling an output of the filter in order to obtain a first magnitude measurement, the first frequency being less than the nominal cut-off frequency; applying a second signal at a second frequency to the input of the filter while sampling the output of the filter in order to obtain a second magnitude measurement, the second frequency being greater than the nominal cut-off frequency; and estimating the cut-off frequency of the filter based on the nominal transfer function, the first magnitude measurement, and the second magnitude measurement.

A device includes an acoustic resonator embedded within an encapsulating structure that at least partially encapsulates the acoustic resonator. The device includes an inductor electrically connected to the acoustic resonator. At least a portion of the inductor is embedded in the encapsulating structure.

A small-sized balance filter includes an unbalanced terminal and two pairs of balanced terminals and has a low signal insertion loss. An unbalanced terminal, a first balanced terminal including first and second terminals, and a second balanced terminal Rx including first and second terminals are provided. An unbalanced-side inductor is provided between the unbalanced terminal and the ground, first balanced-side inductors are provided between the first and second terminals of the first balanced terminal, second balanced-side inductors are provided between the first and second terminals of the second balanced terminal, and the unbalanced-side inductor is electromagnetic-field-coupled to each of the first and second balanced-side inductors.

A CATV & MoCA splitter has an input and at least one output that is CATV & MoCA and at least one output that is MoCA only. The splitter functions as a building block to provide a customizable installation that supplies the needed number of CATV & MoCA outputs and the needed number of MoCA only outputs. The splitter includes a housing with first, second and third coaxial ports attached to the housing. In one embodiment, the second coaxial port is connected to the first coaxial port via a power divider so that all frequencies presented to the first coaxial port can pass to the second coaxial port, and vice versa. A high pass filter, which passes only MoCA signals, connects the power divider and third coaxial port.

A tunable notch filter/amplifier based on the non-reciprocal operation of distributedly modulated capacitors (DMC) formed for an RF front end. In one embodiment within the DMC is formed into a ring resonator with a filter between its ends to allow resonance to build up only at an up-converted frequency, and tune the frequency of the whole received band instead of the resonant frequency of the filter alone. In addition a circulator is described for passing different signals in different directions, but at the same frequency, while maintaining signal separation.