A method of constructing an RF filter comprises designing an RF filter that includes a plurality of resonant elements disposed, a plurality of non-resonant elements coupling the resonant elements together to form a stop band having a plurality of transmission zeroes corresponding to respective frequencies of the resonant elements, and a sub-band between the transmission zeroes. The non-resonant elements comprise a variable non-resonant element for selectively introducing a reflection zero within the stop band to create a pass band in the sub-band. The method further comprises changing the order in which the resonant elements are disposed along the signal transmission path to create a plurality of filter solutions, computing a performance parameter for each of the filter solutions, comparing the performance parameters to each other, selecting one of the filter solutions based on the comparison of the computed performance parameters, and constructing the RF filter using the selected filter solution.

A filter includes shunt circuits coupled between a reference node and each of an input port, an output port, a first node, and a second node. Resonant networks are coupled between the input port and the second node, and between the first node and the output port. Storage element circuits are coupled between the input port and the first node, and between the second node and the output port. The shunt circuits have an equivalent shunt circuit frequency response that partly defines a high passband frequency of the filter, the resonant networks have an equivalent resonant network frequency response that partly defines a low passband frequency of the filter, and the storage element circuits have an equivalent storage element circuit frequency response that defines a stopband frequency of the filter between the low passband frequency and the high passband frequency.

An extensible filter structure is disclosed allowing realizable effective filtering over many decades in frequency. Multiple devices operating with mismatched frequency ranges can be multiplexed together with or without switching.

The invention relates to a filter circuit which, on the hardware level, prevents charge transfers caused by one or more currents in a frequency divider (200) from generating an interference signal that can cause a signal distortion at the output of a current-to-voltage converter (300) belonging to a filter circuit. This signal distortion would otherwise have to be removed by means of laborious post-processing of the signal. In this process, the voltage curve at the input of the frequency divider (200) or the current at the second output of the frequency divider (200) are employed so that, by means of a compensation circuit arrangement, it is possible to model a compensation signal that essentially compensates for an interference signal caused by the charge transfers. The invention also relates to an associated method.

A resonant circuit includes a resonator having a resonant frequency and an anti-resonant frequency, an inductor connected in series to the resonator, an inductor connected in parallel to the resonator, and a series circuit in which a variable capacitor is connected in series to an inductor (15). The series circuit is connected in parallel to the resonator. The anti-resonant frequency closest to the resonant frequency of the resonator is moved toward higher frequencies or lower frequencies of the resonant frequency on a frequency axis with a variation in the capacitance value of the variable capacitor. With this configuration, a resonator device and a high-frequency filter are provided, in which the relationship between a transmission frequency band and a reception frequency band on the frequency axis is applicable to a variety of multiple communication bands.

A filter circuit is provided having multipath interference mitigation. The filter includes a signal path extending from an input to an output. The signal path includes a conductive path and a ground. A pass band filter is disposed along the signal path between the input and the output. The pass band filter passes a first frequency spectrum in a provider bandwidth, and attenuates a second frequency spectrum in a home network bandwidth. The filter circuit further includes a multipath interference mitigation leg operatively branched from the signal path. The multipath interference mitigation leg increases a return loss of the home network bandwidth. A frequency response of the filter circuit is characterized by an insertion loss characteristic between the input and the output being less than 3 dB in the provider bandwidth, and more than 20 dB in the home network bandwidth.

A tunable dual-band resonator and a tunable dual-band band-pass filter using the tunable dual-band resonator. The dual-band resonator is structured such that a stub is added to each half-wavelength resonator provided with half-wavelength resonator protrusions (capacity-component adjust parts). The dual-band resonator is made up of an odd-number mode resonator in a shape including a ground conductor disposed on the back surface of a dielectric body, and a strip conductor disposed on the top surface thereof, and an even-number mode resonator in such a shape as to be formed when the stub is connected to an end face on the opposite side of the open-end of the strip, characterized in that a dielectric rod having a circular cross section is provided in the space above the respective stubs and another dielectric rod having a circular cross section is provided in the space above the half-wavelength resonator protrusions.

A filter includes two series arm resonators electrically connected in series between two input/output terminals, a parallel arm resonator electrically connected between a ground and a series arm between the two series arm resonators, an inductor electrically connected in parallel to the two series arm resonators, and a matching circuit electrically connected between one of the two series arm resonators and one of the input/output terminals, wherein the two series arm resonators and the parallel arm resonator define a pass band of a bandpass filter, the two series arm resonators and the inductor define an LC resonant circuit, respective anti-resonant frequencies of each of the two series arm resonators and a resonant frequency of the parallel arm resonator are located in a pass band of the LC resonant circuit, and a resonant frequency of the LC resonant circuit is lower than the resonant frequency of the parallel arm resonator.

Methods and apparatus, including computer program products, are provided filters. In some example embodiments, there is provided a radio frequency filter including at least one resonant circuit selectable to vary at least the selectivity of the radio frequency filter, wherein the selectivity is varied based on at least one of a first amount of transmit power being used at a user equipment and a second amount of received signal power. Related apparatus, systems, methods, and articles are also described.

A radio frequency (RF) filter circuit for rejecting one or more spurious components of an input signal has a first resonator circuit including a first capacitor and a first coupled inductor pair of a first inductor and a second inductor, and a second resonator circuit with a second capacitor and a second coupled inductor pair of a third inductor and a fourth inductor. First and second resonator coupling capacitors are connected to the first resonator circuit and the second resonator circuit. A first port and a second port are connected to the first resonator circuit and the second resonator, with the filtered signal of the input signal passed through both the first resonator circuit and the second resonator circuit being output.