Abstract: A low-pass filter for use at a user end or an office end in a communication network is disclosed. By providing a capacitive compensation circuit for the low-pass filter, the low-pass filter exhibits an improved attenuation value in a high-frequency band and a general attenuation value in a low-frequency band. The satisfactory attenuation performance in the high-frequency band minimizes the signal interference of a high-band communication terminal with a low-band communication terminal in the communication network. On the other hand, the maintained attenuation value in the low-frequency band allows the low-pass filter to comply with the stipulations of a communication system, e.g. the performance criteria stipulated by TIE1.4.

Abstract: The invention relates to an arrangement for an integrated tunable resonator for radio and a method for producing the same. In particular the invention relates to an RF resonator realized with a micromechanical tunable capacitor with high Q- (quality factor) value and a method for fabricating the same. In one particular embodiment of the arrangement in accordance with the invention the first conducting layer (4) forms the first capacitor electrode (8), and/or the electrodes (9) to create the electrostatic force on the movable micromechanical structure (2), and the interconnecting wire (10) between the inductor coil (1) and the capacitor electrode. The invention presents a substantial improvement to the linearity, power consumption, occupation space and reliability of RF resonator circuits.

Abstract: A compact frequency multiplier can perform high-degree frequency multiplication and can be incorporated in a wireless device. The frequency multiplier includes an input terminal for inputting an input signal, a first resonant circuit resonating with the frequency &ohgr; of the input signal, a second resonant circuit and an idler circuit, which resonate with the frequency n·&ohgr; that is, n times the frequency of the input signal, a variable reactor such as a varactor diode, coupling-adjusting capacitors, a bias resistor, and an output terminal for outputting multiplied output signals. In one embodiment, the frequency multiplier is a current-excitation type. The first resonant circuit and the second resonant circuit, each of which is constituted of an LC series resonant circuit, are connected in series between the input terminal and the output terminal.

Abstract: In an interconnect system for providing access to a common I/O terminal for multiple circuit devices such as drivers, receivers and electrostatic protection devices implemented on an IC, each such device is provided with a separate contact pad within the IC. The contact pads are linked to one another and to the IC I/O terminal though inductive conductors such as bond wires, metalization layer traces in the IC, or legs of a forked, lithographically-defined spring contact formed on the IC. The conductor inductance isolates the capacitance of the circuit devices from one another, thereby improving characteristics of the frequency response of the interconnect system. The inductances of the conductors and various capacitances of the interconnect system are also appropriately adjusted to optimize desired interconnect system frequency response characteristics.

Abstract: A tunable filter (300) includes first (302) and second (304) “bridged-T” resonators. The first (302) and second (304) resonators are capacitively coupled together via bandwidth control/coupling section (306). A biasing section (314) provides the proper biasing and decoupling for the filter (300). Filter (300) provides for low-side injection mode operation, and provides for a very deep zero on the lower side of the passband resulting in excellent selectivity. Filter (300) provides for excellent selectivity while reducing the number of inductors and varactors needed in the filter circuit. A high side injection mode filter (500) similar to filter (300) is also described in the disclosure.

Abstract: The present invention provides for a super-narrow band filter using frequency dependent L-C components. The invention utilizes a frequency dependent L-C circuit with a positive slope k for the inductor values as a function of frequency. The positive k value allows the realization of a very narrow-band filter.

Abstract: A monolithic LC resonator includes insulation sheets and inductor patterns that are electrically connected through long via-holes formed in the insulation sheets. The long via-holes are arranged along the right edge and left edge of the inductor patterns, respectively. The inductor patterns and the long via-holes define an inductor having a tubular structure with a substantially rectangular cross-section and filled with an insulator therein. A capacitor pattern is opposed to the open ends of the inductor patterns through the sheets, respectively, to define a capacitor. That is, the capacitor pattern is laminated inside of the tubular structure of the inductor. The capacitor and the inductor having the tubular structure define an LC parallel resonance circuit.

Abstract: An electrical signal filter including elongate upper and lower filter housing members abutted along a longitudinal seam between the housing members. The housing members hold at least one circuit board having first and second filter sections electrically connected to one another. An isolation shield is formed integrally with at least the lower filter housing member and extends inwardly and upwardly from the inner surface of the lower filter housing member in a direction substantially perpendicular to the longitudinal extension of the housing member. The circuit board has at least one slot for receiving at least a portion of the isolation shield, and is positioned within the filter housing members such that the isolation shield provides magnetic isolation between the first and second filter sections.

Abstract: A reduced length filter including a housing having a female connector end and an opposed male connector end, and a circuit board positioned within the housing. The circuit board has first and second filter sections positioned on upper and lower surfaces thereof, and a ground plane positioned therebetween. The first filter section is in electrical communication with the second filter section. A first isolation shield is provided in electrical communication with the ground plane, and extends from the upper surface of the circuit board in a direction substantially perpendicular thereto and proximate one of first and second ends of the circuit board, and a second isolation shield is provided in electrical communication with the ground plane, and extends from the lower surface of the circuit board in a direction substantially perpendicular thereto and proximate the other one of the first and second ends of the circuit board.

Abstract: A spurious signal reduction circuit which is connected to a main signal line. The spurious signal reduction circuit comprises a resistor having a terminal connected to the main signal line, an LC parallel resonance circuit and an LC series resonance circuit. The parallel resonance circuit has a resonance frequency which is equal to a main signal frequency and has a terminal connected to another terminal of the resistor. The series resonance circuit has a resonance frequency which is equal to a spurious signal frequency and has a terminal connected to the other terminal of the resistor.

Abstract: An LC filter has a ratio of the inductance of an inductor to the capacitance of a capacitor, defining an input-side parallel LC resonant circuit, which is different from a ratio of the inductance of an inductor to the capacitance of a capacitor, defining an output-side parallel LC resonant circuit. The inductor of the input-side parallel LC resonant circuit includes inductor patterns. The inductor of the output-side parallel LC resonant circuit includes different inductor patterns. The capacitor of the input-side circuit includes capacitor patterns. The capacitor of the output-side circuit includes different capacitor patterns.

Abstract: A constant impedance filter maintains a constant input impedance for frequencies that are both inside the filter passband and outside the filter passband. The constant input impedance appears as a pure resistance. The constant impedance filter includes a plurality of filter poles that are connected in series. Each of the filter poles include an inductor, a capacitor, and a resistor. The value of the inductor, the capacitor, and the resistor are selected to provide a constant input impedance over frequency for each pole of the filter, which produces a constant input impedance for the entire filter over frequency. The constant impedance filter can be implemented as a low pass filter, a high pass filter, or a bandpass filter. Furthermore, the constant impedance filter can be implemented in a single-ended configuration or a differential configuration.

Abstract: In accordance with the teachings of this invention a novel method and apparatus is taught which provides for the stabilizing of an output signal through an output circuit having a compensation circuit coupled with an output capacitor, such that the compensation circuit is configured to compensate for an equivalent series resistance of the output capacitor. The compensation circuit compensates for the equivalent series resistance by providing a shift in a phase of the output signal to stabilize the output signal. The shift in phase is accomplished through the addition of a second zero at a second zero frequency to stabilize the output signal. The second zero is added such that the second zero frequency is closer to a first pole frequency than a first zero frequency, where the first pole frequency is proportional to the equivalent series resistance and the first zero is proportional to the output capacitor.

Abstract: To provide a circuit arrangement for filtering and/or selecting single frequencies or frequency ranges, particularly of signals intended for at least an integrated circuit and/or signals generated by at least an integrated circuit, said circuit arrangement (100) comprising at least two electric resonant circuits (10; 20; 30)

Abstract: A filter assembly includes a printed circuit board having a filtering circuit and a ground plane. A body receives the printed circuit board. The printed circuit board has at least one tab, and the body has a respective slot for receiving each tab, aligning the printed circuit board with the body. The body is shaped so as to provide a first cable connector at one end. The ground plane of the printed circuit board is connected to an inner wall of the body by solder. A nut fits on an end of the body opposite the cable connector of the body. The nut provides a second cable connector at an end opposite the first cable connector. The nut is connected to the body by solder along a periphery of the nut to form a water tight seal. The solder joining the nut to the body is continuous with the solder connecting the ground plane to the body. A pair of terminals are electrically connected at opposite ends of the printed circuit board.

Abstract: Elementary electrical resonator (1), characterized in that it comprises:

Abstract: A low-pass filter is defined by a laminate containing an inductor electrode, a plurality of capacitor electrodes, and at least two ground electrodes. The laminate is defined by a plurality of laminated dielectric layers. The low-pass filter includes a grounded capacitor defined by a capacitor electrode and the at least two ground electrodes, the capacitor being located between the ground electrodes, and an ungrounded capacitor including a capacitor electrode which is not located between the ground electrodes.

Abstract: A passive low pass, &pgr;-type filter of a surface mounted device configuration has two stack capacitors disposed radially inwardly of a coil, otherwise known as an inductor. Each capacitor has a number of ground plates successively stacked between a number of signal plates. The ground plates electrically engage a front and rear ground band which circles the external surface of a non-conductive encapsulant of the filter. A forward and rearward conductive member or sheet engages each end of the encapsulant. One end of the coil is engaged to the front sheet and the opposite end is engaged to the rear sheet. The signal plates of the forward capacitor are engaged to the front sheet and the signal plates of the rearward capacitor are engaged electrically to the rear sheet.

Abstract: A bandpass filter comprising a plurality of resonance circuits, in which coils and capacitors are connected in parallel, a first capacitor, which is connected between an input side resonance circuit and an input terminal, and a second capacitor, which is connected between an output side resonance circuit and an output terminal, the plurality of resonance circuits being electromagnetically coupled. The bandpass filter includes the first and second capacitors each face a pair of capacitance electrodes with an insulating layer therebetween, one capacitance electrode of the first capacitor and one capacitance electrode of the second capacitor face each other with an insulating layer therebetween, thereby forming a third capacitor, and another capacitance electrode of the first capacitor and another capacitance electrode of the second capacitor face each other with an insulating layer therebetween, thereby forming a fourth capacitor.

Abstract: Modular thin film, distributed, lumped element band-pass filters. The filter circuitry is configured on a number of ceramic substrates. The component defining depositions are arranged to overlap and couple to one another with connecting vias. Alternative band-pass filter and delay line circuits are disclosed that provide desirable delay characteristics. Bordering ground conductors and covering ground planes shield lumped impedance resonator and overlapping capacitor elements and/or provide a hermetic seal between the layers. The assemblies are configured to accommodate a range of frequencies and permit pre-fabrication with subsequent laser trimming, assembly and packaging.

Abstract: An electronic filter assembly of the type that includes a female terminal cap having a fitting portion and containing a terminal passage through the fitting portion, and a collet assembly secured in and substantially closing the terminal passage of the female terminal cap. The collet assembly comprises an insulator, a collet terminal, and a seal. The insulator is made from a single piece of insulator material, containing a bore therethrough. The collet terminal extends through the bore of the insulator. The seal is located inside the terminal passage of the female terminal cap, between the collet terminal and the female terminal cap.

Abstract: A filter, for use with a delay compensating circuit in a delay line filter, formed from co-located capacitors. The capacitors may be formed as traces disposed on a circuit card and co-located to provide capacitive coupling to each other and ground. Proximity coupling wires are connected at one end to capacitive traces, and at the other end hang in mid-air above the next adjacent capacitive trace. The distance between each proximity coupling wire and the neighboring capacitive trace can be varied to control the capacitance coupling between neighboring capacitive traces. The filter is thus tuned by controlling the distances between the proximity coupling wires, and by squeezing or stretching the inductors. The shunt coils control the frequency of the filter, while the series of capacitive traces control the bandwidth.

Abstract: An IQ generator is integrated into an IC for generating IQ output signal. The IQ generator includes a signal generator providing input with two identical signals opposed in phase, a filter comprises a plurality capacitances and inductances, and output providing the I and Q signals. The capacitances and inductances of the filter are integrated into said integrated circuit.

Abstract: An LC-included electronic component has a greatly reduced size, a greatly increased resonator Q, and outstanding reliability. Inductor via holes are successively connected in a direction in which insulating sheets are stacked to define columnar inductors. The inductor via holes each have a Y-direction dimension greater than an X-direction dimension on the X-Y plane of a section shape, and the shape has Y-direction ends of increased width. Specifically, each Y-direction end of the inductor via holes is substantially circular, and the other portions are linear.

Abstract: A method of producing filters using lower unloaded Q factor components than filters with the same performance characteristics but requiring higher unloaded Q factor components is disclosed. The method includes the steps of defining a desired filter characteristic and applying an algorithm which provides a filter having infinite Q factor elements and having a theoretical characteristic corresponding to the desired characteristic transformed to a compensate for the difference between finite Q factor and infinite Q factor elements.

Abstract: A resonator circuit capable of resonating at a predetermined frequency is provided. The resonator circuit comprises a fixed position coil inductor (62) having a longitudinal axis (92) and a capacitor (88, 82) electrically connected in parallel with each other to form a resonator (60), so that respective first and second ends of the inductor and the capacitor are electrically coupled together at a high-voltage end (64) and a low-voltage end (66) of the resonator (60). A radio frequency (RF) input coupling (70) is coupled directly to the inductor (62) at the low-voltage end (66) of the resonator. A high-voltage electrode (72) is coupled to the high-voltage end (64) of the resonator. A first resonator tuning mechanism is provided for varying the inductance of the inductor, comprising a plunger (90) movable within the coil of the inductor (62) along the longitudinal axis (92). A second resonator tuning mechanism is provided for varying the capacitance of the capacitor (88, 82).

Abstract: A composite filter, with a laminated body formed by laminating a dielectric layer and an electric conductor layer; a concave portion provided on at least one major surface of said laminated body; external terminals provided on at least a side surface of said laminated body; an LC filter made of an inductance element and a capacitance element respectively formed by said electric conductor layer of said laminated body; a surface acoustic wave filter arranged in said concave portion of said laminated body; a cover sealing said concave portion; two of said external terminals constituting the input terminals of said surface acoustic wave filter and of said LC filter respectively and two of said external terminals constituting the output terminals of said surface acoustic wave filter and of said LC filter respectively; and said surface acoustic wave filter and said LC filter are independent without being connected to each other in said laminated body.

Abstract: A wall mount filter for an xDSL network is provided. Wall mount filter includes a wall mount plate to which a connection port is coupled. The connection port is operable to electrically couple to an electronic device. A low pass filter circuit is coupled to a back surface of the wall mount plate. The low pass filter circuit is in electrical connection with the connection port. The low pass filter circuit is operable to electrically couple to a premises network and is sized to fit within a wall mount outlet. The wall mount plate is operable to be coupled to the wall mount outlet with a front surface facing outward and the low pass filter circuit contained within the wall mount outlet.

Abstract: A zero loss bias “T” is provided for use in an RF receiver front end in order to bias a received RF signal with a DC current. The zero loss bias “T” permits a DC current to be introduced into an RF signal path of a filter having filter characteristics sufficient to pass frequencies only in a desired passband without associated losses to the RF signal. The filter may be provided by an LC filter having a ground coupling point. DC current is coupled to the RF signal path of the filter via the ground coupling point.

Abstract: A chip capacitor is arranged on a microstrip conductor forming a microstrip line. The chip capacitor has a dielectric material and electrodes provided on both ends thereof. The electrodes of the chip capacitor are connected to the microstrip conductor. A resonance frequency is decided by the length of the microstrip conductor between the electrodes of the chip capacitor, the dielectric constant and the thickness of the dielectric substrate and the capacitance value of the chip capacitor.

Abstract: A coupling circuit (22) for a radiofrequency (RF) receiver (10) has an attenuator (38) and a resonator (40). Three resistors (42,44,46) of attenuator (38) provide a lossy resistive isolation between a first mixer (20) and a crystal filter (24) of (RF) receiver (10) for undesired signals such as noise and harmonics. Thus, signal reflections between first mixer (20) and crystal filter (24) are absorbed for these undesired signals. However, for desired signals at an intermediate frequency (IF), resonator (40) has an inductor (54) and a capacitor (56) to resonate with such desired signals at the IF. As a result of resonance, resistors (42,46) are isolated to alleviate attenuation of the desired signals.

Abstract: An inexpensive to produce and small profile programmable filter bank with a high quality factor that applies an adjustable frequency response to an input signal to produce a filtered output signal. In a preferred embodiment, the programmable filter bank includes an input for receiving the input signal, an output for transmitting the filtered output signal and a set of interconnected individually selectable filter elements, where each filter element provides a predefined fixed frequency response. A control unit, such as a digital state machine or a microprocessor is connected to the filter elements and enables a user to select one or more filter elements in order to generate a desired overall frequency response, for application to the input signal, that is formed of the combination of the frequency responses of the selected filter element(s).

Abstract: A modular thin film, distributed, lumped element band-pass filter. The filter circuitry is configured on a number of ceramic substrates. The component defining depositions are arranged to overlap and couple to one another with connecting vias. Alternative 800 MHz and 1.9 GHz band-pass filter circuits are disclosed. Bordering ground conductors and covering ground planes shield lumped impedance resonator and overlapping capacitor elements. The layers are configured to accommodate a range of frequencies and permit pre-fabrication with subsequent laser trimming, assembly and packaging.

Abstract: A channelized active bandpass filter having only two branches which provide respective frequency-selective feed-forward signal paths. The two signal aths have overlapping frequency response bands such that the combination of the two paths provides a composite filter with a bandpass response. The two branches may be provided with bandpass transfer characteristics of different orders and shapes, such as a second-order response and a fourth-order response. Two-way signal splitting and combining to define the two channels may be performed with in-phase splitters and combiners, for example, or diplexer circuits, each composed of two bandpass filters with different characteristics but overlapping frequency responses and preferably approximately equal center frequencies. Combinations of the two splitting and combining arrangements are also usable.

Abstract: A tunable filter (400) provides dual injection mode operation over a continuously tunable frequency range (500). A combination of mirrored series resonant circuits (432, 446) tuned through varactors (434, 448) allows the frequency response to shift. The use of a series capacitor and shunted inductor (430, 428), (444, 442) mirrored onto each series resonator (432, 446) provides both high-side and low-side injection protection.

Abstract: A receiving apparatus is presented, in which a channel frequency can be selected over a wide band with an increased attenuation at an image frequency and/or at a local oscillation frequency by including a tunable filter having a following construction. Microstrip lines are connected between either one of the input or the output terminal or both of the input and output terminals of the tunable filter; a plurality of resonant circuits are formed by each of a plurality of coils and a plurality of variable capacitance diodes; and the coils are electromagnetically coupled and where a voltage applied to each cathode of each of a plurality of variable capacitance diodes through each of a plurality of resistors is controlled to tune a frequency to be received.

Abstract: The inventive bandpass filter is suitable for use in a multi-layer ceramic (MLC) structure. Specifically, the filter is a semi-lumped type, formed by lumped capacitors and distributed transmission lines. Preferably, shorted transmission lines are used as equivalent inductors, which are connected with high value lumped capacitors to form resonators. Accordingly, the size of the resonators can be much smaller than 1/4 of the signal wavelength. The bandpass filter preferably has attenuation poles very close to lower passband edge, which results in a very sharp rejection near the stopband. The inventive filter may be utilized as a receiver-end filter in, e.g., duplexer applications or for miniaturized applications, such as portable communications.

Abstract: A multilayer microelectronic circuit to be directly mounted on a substrate and to be used, for example, as a resonator. The multilayer microelectronic circuit comprises a plurality of dielectric layers and patterned electrodes which are laminated one upon another to form a laminated structure, the dielectric layers and the patterned electrodes forming an electrical circuit. The laminated structure has side surfaces extending along a direction in which the dielectric layers and the patterned electrodes are laminated. An input line is formed at one of the side surfaces and connected with an input section of the electrical circuit. An output line is formed at one of the side surfaces and connected with an output section of the electrical circuit. A grounding line is formed at one of the side surfaces and connected with a grounding section of the electrical circuit. Additionally, a signal line formed at one of the side surfaces, for connecting sections of the electrical circuit.

Abstract: An interactive game is disclosed which may take the form of a board game, a hand held game or a yard game. It includes a series of printed circuits or devices which may be concealed within a playing surface and an electronic detector for the circuits. Easily as many as 8 or 16 different discrete device may be detected and distinguished. Stored messages associated with each device or combinations of devices is displayed or audibly reproduce the messages.

Abstract: The invention provides a composite filter, comprising: a laminate formed by laminating a dielectric layer and a conductor layer; a concave portion provided on at least one major surface of said laminate; a plurality of external terminals provided at least on a side surface of said laminate; a cap sealing the concave portion; a surface acoustic wave filter disposed in said concave portion of said laminate; a LC filter provided within said laminate, said LC filter comprising an inductance element and a capacitance element made of said conductor layer respectively; two of said external terminals being input terminals of said surface acoustic wave filter and said LC filter respectively; and other external terminal being a common output terminal of said surface acoustic wave filter and said LC filter.In the above composite filter, the number of components is reduced and the assembly process can be simplified.

Abstract: A radio frequency (RF) coupler transfers RF power between a first circuit on a rotary shaft and a second circuit relative to which the shaft can rotate. The coupler comprises a first RF transmission line arranged to rotate with the rotary shaft about the rotation axis of the rotary shaft for connection to the first circuit and a second RF transmission line relative to which the first RF transmission line can rotate for connection to the second circuit. The first and second RF transmission lines comprise first and second electrically conductive tracks arranged coaxially around the rotation axis in mutually overlapping relationship to provide RF coupling between the first and second RF transmission lines. Each track has a gap defining a pair of ports. One of the ports of each track is connectable to a respective circuit and another port in the track is connected to a RF reflecting termination. A notch filter tunable to a desired frequency within a predetermined RF band is also described.

Abstract: Disclosed is a new single-phase passive harmonic filter for one or more nonlinear loads. The filter improves the total system performance by drastically reducing the line side current harmonics generated by nonlinear loads. The filter includes two inductive portions across one of which is connected a tuning capacitor. The parallel combination of one inductive portion with the tuning capacitor forms a series tuned filter configuration while the second inductive portion is used for harmonic attenuation. A shunt capacitor is employed for shunting higher order harmonic components. A single-phase passive voltage regulator provides the needed voltage bucking to prevent over voltage at the load terminals of the filter. The filter provides an alternate path for the harmonic currents generated by nonlinear loads. The over voltage caused by the increased capacitive reactance is controlled by either capacitor switching or by the use of the passive voltage regulator or a combination of the two.

Abstract: An interface module having a receiving section and a sending section, the receiving section being provided with a low pass filter, an isolation transformer and a common mode choke transformer, and the sending section is provided with a low pass filter, an isolation transformer and a common mode choke transformer and they are integrated with each other, wherein the receiving section and the sending section are independently formed on a board of the interface module, and the low pass filter at the receiving section and the low pass filter at the sending section are respectively covered by shield cases.

Abstract: An impedance matching circuit for a multi-band power amplifier has an input port for receiving RF signals from an amplifier, a first path for communicating RF signals in a first frequency band to a first output port, and at least one second path for communicating RF signals in a second frequency band to a second output port. The first path includes impedance matching circuitry for matching the impedance of the first output port and the input port in the first frequency band, and the second path includes impedance matching circuitry for matching the impedance of the second output port and the input port in the second frequency band. The first path contains circuitry which blocks RF signals in the second frequency band, and the second path contains circuitry which blocks RF signals in the first frequency band. A multiband power amplifier includes a multi-band amplifier coupled with an impedance matching circuit for a multiband power amplifier.

Abstract: There is provided a chip type filter which can be made compact, allows the matching of input/output impedance, and has preferable characteristics. A ground electrode is formed on one side of a dielectric substrate, and spiral-shaped pattern electrodes are formed on the other side. Input/output electrodes are led out from intermediate portions of the pattern electrodes. Curved portions are formed between the input/output electrodes and the ends of the pattern electrodes. The ends of the pattern electrodes are positioned close to each other. Protective layers are formed on the ground electrode and pattern electrodes, which are laminated and integrated to form external electrodes. The ends of the pattern electrodes and the ground electrode are connected by one of the external electrodes.

Abstract: A multilayer ceramic package (200) with a floating element (202) to couple transmission lines (214) is disclosed. The package (200) has numerous dielectric layers (204A-204I) including an input electrode (206), an output electrode (208), a top ground plane (210) and a bottom ground plane (212). Transmission lines (214) are formed on some of the dielectric layers (204A-204I). Floating element (202) adjusts the electrical coupling between the transmission lines (214) and is spatially separated therefrom. This may provide the advantage of increased capacitive coupling between transmission line resonator structures in a multilayer packages, including non-adjacent resonant structures, without increasing the overall dimensions of the package (200). The floating element (202) may also increase the operable passband of a multilayer bandpass filter or provide a low-side transmission zero.

Abstract: A filter network adapted to be placed in parallel with a power supply which acts like a short circuit at a specified frequency range above 80 kHz. The filter network comprises a plurality of parallel circuits, each of which comprise a capacitor, an inductor and a resistor in series with a second resistor coupled in parallel with the inductor.

Abstract: In an RF filter having an input terminal, an output terminal, a plurality of resonator elements, and a plurality of coupling reactances for coupling one resonator element to another resonator element, for coupling the input terminal to a resonator element, and for coupling the output terminal to a resonator element, techniques are disclosed for providing an RF filter having an electronically tunable center frequency and an electronically tunable bandwidth. According to a specific embodiment disclosed herein, a first shunt reactance is provided from the input terminal to ground, and a second shunt reactance is provided from the output terminal to ground. The values of the coupling reactances remain constant, while the values of the resonator elements, the first shunt reactance, and the second shunt reactance are tuned to provide a specified filter bandwidth and/or a specified center frequency.

Abstract: Dielectric sheets 2 having internal electrodes 4 and 5 formed on the respective surfaces thereof, a dielectric sheet 2 having an outgoing electrode 6 formed on the surface thereof, and a dielectric sheet 2 having a shielded electrode 3 formed on the surface thereof are piled and integrally sintered to form a lamination. Grounding external electrodes are formed on first and second opposite sides of this lamination, respectively, and an input/output external electrode is formed on a third side thereof. An end portion 4a of the internal electrode 4 and an end portion 3a of the shielded electrode 3 are connected to the grounding external electrode on the first side. An end portion 5a of the internal electrode 5 and an end portion 3b of the shielded electrode 3 are connected to the grounding external electrode on the second opposite side. An end portion 6a of the outgoing electrode 6 is connected to the input/output external electrode on the third side.

Abstract: In a filter unit having a first and a second bandpass filter (21 and 22) and an input terminal (101) supplied with a unit input signal, the first bandpass filter has a first filtering bandwidth with a first center frequency while a second bandpass filter having a second filtering bandwidth with a second center frequency. Only when the unit input signal has a bandwidth similar to the first filtering bandwidth, a first impedance-adjusting arrangement (11 and 31) matches a first impedance of a combination of the first bandpass filter and the first impedance-adjusting arrangement with an output impedance of an input side component. Only when the unit input signal has a bandwidth similar to the second filtering bandwidth, a second impedance-adjusting arrangement (12 and 32) matches a second impedance of a combination of the second bandpass filter and the second impedance-adjusting arrangement with the output impedance of the input side component.