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.

A cascading microwave switch (cascade) includes a set of Josephson devices, each Josephson device in the set having a corresponding operating bandwidth of microwave frequencies, wherein different operating bandwidths have different corresponding center frequencies. A series coupling is formed between first Josephson device from the set and an n.sup.th Josephson device from the set, wherein the series coupling causes the first Josephson device in an open state to reflect back to an input port of the first Josephson device a signal of a first frequency from a frequency multiplexed microwave signal (multiplexed signal) and the n.sup.th Josephson device in the open state to reflect back to an input port of the n.sup.th Josephson device a signal of an n.sup.th frequency from the multiplexed signal.

Methods and system for using a multifunctional filter to minimize insertion loss in a multi-mode communications system are described. Specifically described is a multifunctional filter that is configurable to operate in a band-pass mode when a first type of signal is propagated through the multifunctional filter, and to operate in a low-pass mode when a second type of signal is propagated through the multifunctional filter. The multifunctional filter presents a lower insertion loss to the second type of signal when operating in the low-pass mode than in the band-pass mode.

A filter circuit for use with a system configured to be coupled with an electrical load, the filter circuit comprising a first filter, wherein the first filter is configured to receive a first voltage and provide an output voltage, the output voltage being the first voltage after filtering by the first filter, and the filter circuit is configured to adjust the bandwidth of the first filter in response to a load transient.

A bandpass filter circuit includes a fourth element that is a capacitor having one end connected to a first node, a fifth element that is a capacitor having one end connected to a second node, a sixth element that is a capacitor connected between other end of the fourth element and other end of the fifth element, a seventh element that is an inductor having one end connected to a fourth node to which the fourth element and the sixth element are connected, other end of the seventh element is connected to a ground terminal, and an eighth element that is an inductor having one end connected to a fifth node to which the fifth element and the sixth element are connected, other end of the eighth element is connected to the ground terminal.

Described embodiments include a circuit having a quadrature phase generator circuit having differential generator inputs, in-phase differential generator outputs and quadrature-phase differential generator outputs. A first frequency multiplier circuit has first differential multiplier inputs and a first multiplier output, wherein the first differential multiplier inputs are coupled to the in-phase differential generator outputs. A second frequency multiplier circuit has second differential multiplier inputs and a second multiplier output. The second multiplier differential inputs are coupled to the quadrature-phase differential generator outputs. A transformer includes a primary inductor and a secondary inductor, wherein the primary inductor is coupled between the first and second multiplier outputs, and the second inductor is coupled between an output voltage terminal and a ground terminal.

A band-pass filter for a wireless communications signal is provided. The band-pass filter includes a first element and a second element that mates with the first element to form a waveguide. The formed waveguide comprises a first linear segment and a second linear segment coupled by a first angular bend. The band-pass filter further includes an insert plate disposed between the first element and the second element along a direction of propagation of the waveguide. The direction of propagation follows the angular bend in the waveguide. In some embodiments, the band-pass filter is an E-plane filter. In some embodiments, the band-pass septum filter has a shorter length along an x-direction than a straight septum filter with the same performance.

The invention relates to an RF filter with reduced insertion loss. The filter (F) includes a first bandpass filter (BPF1) having a passband, a circuit unit (SE) having an undesired excitation at a critical frequency (f.sub.s) and a reflector (R) that reflects RF signals of this frequency before the circuit unit is undesirably excited and the power is lost as a result.

An apparatus according to one embodiment includes a hardware based controller that is configured to perform operations. The operations include performing anti-aliasing filtering on each of a plurality of signals, each signal having a frequency that is a different fraction of a frequency of a data read clock. An amplitude is measured of each of the signals after the anti-aliasing filtering. Moreover, the operations include determining whether the measured amplitudes of the signals are within a predefined range. Anti-aliasing settings used during the anti-aliasing filtering are stored in response to a determination that the amplitudes of the signals are within the predefined range. The anti-aliasing settings are changed in response to a determination that the amplitudes of the signals are outside the predefined range.

A filter (11) includes a series-arm circuit (10) connected between an input/output terminal (11m) and an input/output terminal (11n); and a parallel-arm circuit (20) connected between a ground and a path that connects the input/output terminal (11m) and the input/output terminal (11n). One circuit among the series-arm circuit (10) and the parallel-arm circuit (20) is constituted by a parallel-arm resonator (p1) and a parallel-arm resonator (p2) that are connected in parallel to each other and that are connected to a node (x1) on the path. The parallel-arm resonators (p1) and (p2) form a pass band, together with another circuit among the series-arm circuit (10) and the parallel-arm circuit (20). The parallel-arm resonator (p2) has a resonant frequency lower than a resonant frequency of the parallel-arm resonator (p1) and has an impedance higher than an impedance of the parallel-arm resonator (p1).