Abstract: A tunable RF filter comprises a signal transmission path having an input and output, a plurality of resonant elements disposed along the signal transmission path between the input and output, and a set 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 at least one sub-band between the transmission zeroes. The set of non-resonant elements comprises a first plurality of non-resonant elements respectively coupled in parallel with the resonant elements, and a second plurality of non-resonant elements respectively coupled in series with the resonant elements. The first plurality of non-resonant elements comprises at least one variable non-resonant element for selectively introducing at least one reflection zero within the stop band to create a pass band in one of the one sub-band(s) without varying any of the second plurality of non-resonant elements.

Abstract: A varactor element having a junction region, in which the depletion capacitance of the varactor element varies when a reverse bias voltage is applied to the varactor element. The varactor element has an exponential depletion capacitance-voltage relation, e.g. obtained by providing a predetermined doping profile in the junction region. The varactor element can be used in a narrow tone spacing varactor stack arrangement, in which two varactor elements are connected in an anti-series configuration. A low impedance path for base band frequency components between a control node and each of two RF connection nodes is provided, while for fundamental and higher order harmonic frequencies, a high impedance path is provided.

Abstract: A filter circuit topology for filtering a radio frequency input signal includes one or more inductor devices, such as, for example, discrete chip or air coils. The inductor devices are center tapped into a capacitor coupled to the ground. The center-tapped inductor configuration splits the output voltage across the inductor devices into two equal voltages of predetermined amplitude determined by the quality factor of the filter circuit. The filter circuit further includes an input capacitor to receive the RF input signal and an output capacitor coupled respectively to the inductor devices, the output capacitor having a variable capacitance, the inductor devices and the variable capacitor forming an inductive-capacitive (LC) filter capable of filtering the RF input signal and generating an output filtered signal for further transmission to a television tuner.

Abstract: A low-pass filter comprises a capacitor, first and second varistors, a resistor, and first to third external electrodes. The capacitor includes a dielectric body and first to third internal electrodes. The first internal electrode is connected to the third external electrode physically and electrically. The second internal electrode is connected to the second external electrode physically and electrically. At least a portion of the second internal electrode opposes the first internal electrode through at least a portion of the dielectric body. The third internal electrode is connected to the first external electrode physically and electrically. At least a portion of the third internal electrode opposes the first internal electrode through at least a portion of the dielectric body. The first varistor is connected in parallel to a capacitor constituted by the first and third internal electrodes. The second varistor is connected in parallel to a capacitor constituted by the first and second internal electrodes.

Abstract: The invention relates to a compact power-agile filter. The filter is a capacitance-weight filter comprising two electromagnetically-coupled oscillating circuits. Each oscillating circuit comprises capacitance weights. Each capacitance weight is controlled by signals. The filter comprises at least one motherboard and one daughterboard which are physically separate. The daughterboard comprises the capacitance weights, the motherboard comprises all the oscillating circuits. In particular, the invention applies to the power filter included in a radiocommunication system amplification module. For example, the invention can be used by a radiocommunication system that can be programmed by software means adapting to a range of signals extending over a wide frequency band.

Abstract: An automatic tuning apparatus for a filter includes a mode wherein a switching part is controlled so that a reference signal is inputted to the filter, a plural number of control signals are successively input to a control terminal of the filter, a tentative value of the control signal is determined based on respective amplitudes detected by an amplitude detection part as a “coarse tuning step”, a plural number of control signals are successively input in the vicinity of the tentatively determined value to a control terminal, and the value of the control signal is determined to be used in a mode as a “fine tuning step” based on respective phase differences detected by a phase comparator part”.

Abstract: A description is given of a high frequency filter comprising microstrips. The filter comprises at least two resonators (16, 18) which each have, as frequency-determining elements, a first straight microstrip section (28) and a second straight microstrip section (30), which are parallel next to each other, and also a capacitor assembly (22). In each resonator the capacitor assembly is connected between first ends of the microstrip sections and each resonator is exclusively connected to ground at the second ends of the microstrip sections. In each resonator (16, 18) the sum of the two microstrip sections acts as inductive lement. The resonators (16, 18) therefore act in the same manner as a resonator having a single microstrip, the length of which corresponds essentially to the sum of the lengths of the first microstrip section (28) and the second microstrip section (30). This construction of a filter allows a shorter design compared to conventional filter structures.

Abstract: A variable resonator includes a ring-shaped conductor line (2) which is provided on a dielectric substrate (5) and has a circumferential length of a wavelength at a resonance frequency or an integral multiple of the wavelength, and at least two circuit switches (31, 32), wherein the circuit switches (31, 32) have one ends (31) electrically connected to the ring-shaped conductor line (2) and the other ends (32) electrically connected to a ground conductor (4) formed on the dielectric substrate (5), electrical connection/disconnection between the ground conductor (4) and ring-shaped conductor line (2) can be switched, and the one ends (31) of the circuit switches (31, 32) are connected to the ring-shaped conductor line (2) on different portions.

Abstract: According to an embodiment of the present invention, a microelectromechanical system (MEMS) element tunes a resonator to a frequency.

Abstract: An absorptive bandstop filter includes at least two frequency-dependent networks, one of which constitutes a bandpass filter, that form at least two forward signal paths between an input port and an output port and whose transmission magnitude and phase characteristics are selected to provide a relative stopband bandwidth that is substantially independent of the maximum attenuation within the stopband and/or in which the maximum attenuation within the stopband is substantially independent of the unloaded quality factor of the resonators. The constituent network characteristics can also be selected to provide low reflection in the stopband as well as in the passband. The absorptive bandstop filter can be electrically tunable and can substantially maintain its attenuation characteristics over a broad frequency tuning range.

Abstract: A tunable wideband bandpass filter that can digitally vary the center frequency and bandwidth of a signal to be filtered, and includes a plurality of switched-capacitor banks for varying capacitance and converting the center frequency and bandwidth into a digital signal, and a plurality of inductors provided for inductance to generate the center frequency, the plurality of switched-capacitor banks that may be integrated into a signal chip.

Abstract: In a variable matching circuit including an impedance device and a variable-capacitance capacitor, the variable-capacitance capacitor is formed in a manner that a plurality of variable-capacitance devices using thin film dielectric layers whose dielectric constants change depending on applied voltages are connected to each other in parallel regarding a direct current and connected to each other in series regarding a high frequency, between an input terminal and an output terminal. The variable matching circuit can be realized that can make the maximum use of the rate of a capacitance change of the variable-capacitance capacitor by a bias signal and make an impedance matching, that exhibits small waveform distortion and intermodulation distortion, and that is excellent in electric high power handling capability and low-loss even at a high frequency.

Abstract: In general, the invention is directed to a tunable inductor that makes use of eddy current effect to tune the inductance of an inductor. The tunable inductor may include a spiral or helical inductor in proximity to one or more sets of eddy current coils. Each eddy current coil may be coupled to a corresponding switch that controls whether the eddy current coil is grounded or floating. In operation, a first time-varying current through the inductor induces a first magnetic field that, in turn, induces a time-varying voltage in an eddy current coil. If the eddy current coil is not grounded, an eddy current flows through the eddy current coil. The eddy current, which flows in the opposite direction of the first time-varying current, induces a second magnetic field. The second magnetic field, which opposes the first magnetic field, reduces the inductance of the tunable inductor.

Abstract: A discrete inductive-capacitive (LC) filter selects between at least two inductor banks to tune the LC filter. The filter receives an input signal that includes one or more bands of frequencies. A control signal selects a band of frequencies for processing. A first inductor bank is selected to filter a first band of frequencies, and a second inductor bank is selected to filter a second band of frequencies. A switch circuit couples the input signal to either the first inductor bank or the second inductor bank. The switch circuit selects the first inductor bank if the first band of frequencies is selected, and selects the second inductor bank if the second band of frequencies is selected. The switch circuit electrically isolates the switching of the input signal to the first and the second inductor banks, so as to enhance the Q factor of the LC filter. Circuit and techniques are disclosed to reduce parasitic capacitance in a capacitive bank that employs MOS transistors.

Abstract: This invention provides a voltage tunable filter comprising an input connection point, an output connection point, and at least one circuit branch electrically coupled to the input connection point and the output connection point and including a voltage tunable dielectric varactor electrically connected to an inductor. The voltage tunable filter can be one of a low-pass, high-pass, band-pass, or band-stop filter. The varactor can include built-in DC blocking capacitors.

Abstract: A method and apparatus for providing dynamic and remote tuning of a cryo-cooled bandpass filter is disclosed. The device includes resonator element and a voltage sensitive element as part of the capacitance in a narrow band filter circuit. A varactor such as a GaAs varactor may be used. Alternatively, a capacitor having a voltage-sensitive dielectric such as SrTiO3 may be used. A computer may be connected to the varactor to provide for automated tuning. The voltage-sensitive capacitor may be integral with the resonator element. The invention provides for remote and dynamic tuning of a narrow bandpass filter while located within its sealed cryo-cooled environment.

Abstract: In a receiver, provision is made of a tuneable switchable bandpass filter comprising a primary resonant circuit and a first secondary resonant circuit. A second secondary resonant circuit can be switched into a part of the first primary resonant circuit, thereby producing a second primary resonant circuit. By virtue of the embodiment of the primary resonant circuit, the bandpass filter is switchable in terms of frequency range with little outlay on circuitry and, on account of the individual embodiment of a first and second secondary resonant circuit with individual coupling elements, can be optimized with regard to a constant amplitude response.

Abstract: An inductive (“L”)-capacitive (“C”) filter bank has application for use in a television receiver. The LC filter includes inductors configured in at least one inductive (“L”) bank, and capacitors configured in at least one capacitive (“C”) bank. The inductors and capacitors are selectively enabled so as to configure an LC filter with at least one inductor from the L bank and at least one capacitor from the C bank. A combination of inductors and capacitors are selected through the semiconductor switches so as to maximize a Q factor for the LC filter.

Abstract: A MEMS tunable capacitor with angular vertical comb-drive (AVC) actuators is described where high capacitances and a wide continuous tuning range is achieved in a compact space. The comb fingers rotate through a small vertical angle which allows a wider tuning range than in conventional lateral comb drive devices. Fabrication of the device is straightforward, and involves a single deep reactive ion etching step followed by release and out-of-plane assembly of the angular combs.

Abstract: A calibration circuit and method causes a cutoff frequency to match the design frequency of low pass filter by adjusting a capacitor array in the low pass filter.

Abstract: A circuit for correcting the offset of an amplification and filtering chain having a predetermined gain and cut-off frequency depending on the value of at least one capacitor, comprising: a correction means for subtracting from the chain input a correction signal depending on the value of a programmable digital word; a digital automaton for, in a setting phase, searching, then memorizing one of two consecutive values of the digital word between which the output signal of the chain switches sign, the input signal being canceled during a setting phase; and comprising a means for, during the setting phase, reducing the value of said at least one capacitor with respect to its normal operating value.

Abstract: A tunable high-order Bessel low pass filter which is applied to a multi-rate duobinary generation system of an optical communication system.

Abstract: An apparatus for reducing influence by selected signal components in a communication link includes a first signal line conveying a first communication signal including a desired signal component and at least one undesired signal component; a second signal line conveying a second communication signal substantially including at least the at least one undesired signal component; a signal treating unit coupled with the second signal line for affecting at least one parameter associated with the second communication signal to present a modified second communication signal at a first output locus coupled for combining the modified second communication signal with the first communication signal to present an improved communication signal at a second output locus. The at least one undesired signal component affects the improved communication signal less than the at least one undesired signal component affects the first communication signal.

Abstract: A noise filter of the present invention includes an inductor and a resistor connected in parallel with each other. A power supply frequency current does not pass the resistor but passes through the inductor with no loss. On the other hand, a high frequency noise current including a resonance frequency current, does not pass the inductor but is dissipated at the resistor. Therefore, the noise filter does not charge noise power and so does not suffer from a problem due to power discharging. The resonance frequency current caused by the noise filter and the earth capacitance is also dissipated at the resistor. Therefore, no problem is caused by the resonance frequency current.

Abstract: A tuning circuit for use in an electrical circuit network is disclosed. The tuning circuit includes a bridge circuit. The bridge circuit comprises a first adjustable capacitance grouping, a second adjustable capacitance grouping and a third adjustable capacitance grouping. Each adjustable capacitance grouping includes at least one tunable capacitor and a bias port. In one embodiment, the tunable capacitor is comprised of a tunable thin-film barium strontium titanate (“BST”) capacitor. A first lead and a second lead couple to, or extend from, the bridge circuit. The leads are configured to couple with a coupling element and a shunt element of the electrical circuit network so that when the leads are grounded, one adjustable capacitance group is grounded and the remaining adjustable capacitance group couple with a bias voltage to appropriately tune the electrical circuit to achieve desired electrical characteristics.

Abstract: There is disclosed a variable capacitance circuit which comprises: first to Nth variable capacitance elements C1-CN (N is an odd number) sequentially connected in series between an input terminal I and an output terminal O, whose capacitances change depending on voltage applied thereto; an ith bias line on the input terminal side provided between an input terminal portion of the first variable capacitance element and a connection point between a 2ith variable capacitance element and a (2i+1)th variable capacitance element; and an ith bias line on the output terminal side provided between an output terminal portion of the Nth variable capacitance element and a connection point between a (2i?1)th variable capacitance element and the 2ith variable capacitance element, where N and i are integers satisfying N=2n+1, n?1, 1?i?n.

Abstract: Disclosed is apparatus for operating with an RC filter (26, 26A), and a corresponding method. The apparatus includes circuitry (32) for use in measuring an actual value of at least one filter component and a controller (34), coupled to the measurement circuitry, for determining at least one adaptive filter (36, 46) coefficient using the measured actual value to so as to compensate for a deviation of at least one filter component value from an ideal value. Where the filter is embodied as an RC network, the circuitry measures an actual value of both a resistor and a capacitor, and the controller uses the measured actual value of the capacitor when determining the value of a resistor.

Abstract: An adjustable phase shifter generates a phase shifted reference signal by introducing a phase shift in a reference signal. A phase detector identifies a phase difference between the reference signal and the phase shifted reference signal. A control signal generator generates a plurality of control signals, each of which causes the adjustable phase shifter to adjust a magnitude of at least one component value in the adjustable phase shifter. The phase shift introduced by the adjustable phase shifter is based at least partially on the magnitude of the at least one component value in the adjustable phase shifter. The control signal generator also selects one of the control signals, where the selected control signal causes the adjustable phase shifter to produce the phase shifted reference signal such that the phase difference attains a specified value. The analog filter adjusts a magnitude of at least one component value in the analog filter based at least partially on the selected control signal.

Abstract: The invention provides a filter network comprising a plurality of circuit branches, each circuit branch comprising one or more filter elements. At least one of the circuit branches comprises a resonant circuit and is preferably arranged between the circuit path and ground. The filter network further comprises a switch device associated with the resonant circuit, the switch device being operable between an on state, in which the resonant circuit is connected to said circuit path, and an off state in which the resonant circuit is substantially isolated from said circuit path. The filter network also includes a switch control input for receiving a signal for operating the switch device between the on and off states. Switching in and out the resonant circuit changes the operational characteristics of the filter.

Abstract: A continuously variable waveguide filter (100). The variable waveguide filter can include at least one waveguide filter cavity (154, 156, 158) and a fluid dielectric (108) having a permittivity and a permeability at least partially disposed within the waveguide filter cavity (154, 156, 158). At least one composition processor (101) is included and adapted for dynamically changing a composition of the fluid dielectric (108) to vary at least one electrical characteristic. A controller (136) is provided for controlling the composition processor (101) in response to a waveguide filter control signal (137).

Abstract: A method and an apparatus for tuning a filter is provided wherein the filter has at least one adjustable element for adjusting at least one performance parameter of the filter like for example a cut-off frequency, wherein a pseudo-random test sequence is applied to the filter, wherein the cross-correlation function of the test sequence and the filtered test sequence is calculated, and wherein the at least one adjustable parameter is adjusted until the cross-correlation function at at least one point basically coincides with a corresponding point of a nominal cross-correlation function for the filter.

Abstract: A method for tuning a filter to a desired frequency using successive approximation. Elements of the filter are selected according to a control code used to vary the filter's oscillation frequency. The control code is set to the middle of the control code range and resulting oscillation frequency is compared to the desired frequency. If the control code needs to be increased, the control code is set to ¾ of the control code range. If the control code needs to be decreased, the control code is set to ¼ of the control code range. The method continues using successive approximation to determine the value of each bit of the control code. Thus, successive approximation is used to converge on the value of the control code that produces an oscillation frequency of the filter that is closest to the desired frequency (with a maximum error of 1 least significant bit).

Abstract: An apparatus for improving the stop band response of a surface acoustic wave device (200) comprising a surface acoustic wave device (200) having internal electromagnetic coupling (106) and external electromagnetic coupling (108) and acoustic coupling (104); and a cancellation network (250, 251) coupled to the surface acoustic wave device to reduce the internal electromagnetic coupling (106) and external electromagnetic feed through (108); wherein the cancellation network (250, 251) reduces the amount of electromagnetic feed through at the output (102) of the surface acoustic wave device (200).

Abstract: A ferro-electric filter and method of tuning same. The filter includes a switch for switching between quarter wave resonator and half wave resonator modes. The filter also includes a ferro-electric component for tuning the resonant frequency. The method includes applying a switching control signal to the switch for switching between resonant frequencies and applying a tuning control signal for tuning the resonant frequency.

Abstract: A tunable filter having a fixed substrate, a first and second plate comprising a high-temperature superconductor material on the fixed substrate, a movable substrate, a mechanical driver attached to the fixed substrate and the movable substrate, a floating plate comprising a high-temperature superconductor material on the fixed substrate wherein the floating plate, the first plate, and the second plate define a gap, and wherein the gap is varied by length changes in the mechanical driver is provided.

Abstract: A novel transceiver is provided which allow for either a transmitter or receiver to be dynamically switched between two different frequency bands by use of a novel switchable lowpass filter.

Abstract: A system and method for a filter tuner is presented. The system comprises a sequential logic, a register, a comparator, a first and second counter, a synchronizing logic, a first and second oscillator, a control logic, and a first and second combinational logic. The method comprises the steps of executing a calibration cycle of a filter tuner, executing a measurement cycle of the filter tuner, and tuning a filter with the filter tuner dependent on a determined cutoff frequency variation.

Abstract: An integrated component for radiofrequency applications has a resonant circuit with tuning diodes and trimming diodes that are connected in parallel. A programmable conductor network generates a trimming voltage at a trimming input that enables the production of a specific relationship between a voltage present at a tuning input and the resonant frequency of the resonant circuit.

Abstract: A continuously variable filter (110) that includes at least one filter element (146). The filter also includes a fluidic dielectric (108) having a permittivity and a permeability, a composition processor (101) adapted for dynamically changing a composition of the fluidic dielectric (108), and a controller (136) for controlling the composition processor (101) to selectively vary the permittivity and/or the permeability in response to a filter control signal (137). The filter element (146) is at least partially coupled to the fluidic dielectric (108). A second fluidic dielectric having a different composition than the first fluidic dielectric can be provided and a second filter element (148) can be partially coupled to the second fluidic dielectric. The controller (136) and composition processor (101) also can be adapted for varying the permittivity and/or permeabiliity of the fluidic dielectric (108).

Abstract: A novel system and method for a frequency tunable filter is described. The inventive system and method may be used, for example, in multi-band cellular phones and/or transceivers in wireless networks. The inventive system and method avoids the creation of undesired spurs thus minimizing design difficulties and obviating the need for complex multiple frequency conversions and the associated deleterious effects on performance. The inventive system and method provides at an output terminal an output signal at one of a plurality of predetermined frequencies.

Abstract: An inductive (“L”)-capacitive (“C”) filter bank has application for use in a television receiver. The LC filter includes inductors configured in at least one inductive (“L”) bank, and capacitors configured in at least one capacitive (“C”) bank. The inductors and capacitors are selectively enabled so as to configure an LC filter with at least one inductor from the L bank and at least one capacitor from the C bank. A combination of inductors and capacitors are selected through the semiconductor switches so as to maximize a Q factor for the LC filter.

Abstract: A variable RF filter (102) which includes one or more filter elements (104,106). The filter elements (104,106) can be formed from a structure selected from the group consisting of stripline, microstrip, and buried microstrip. A fluid dielectric (108) and a fluid control system (150) for selectively moving the fluid dielectric from a first position to a second position are provided. In the first position, the fluid dielectric (108) is electrically and magnetically coupled to the filter elements (104,106) to produce a first filter response. In the second position, the fluid dielectric (108) is electrically and magnetically decoupled from the filter elements (104,106) to produce a second filter response distinct from the first filter response. The first position can be defined by a bounded region located adjacent to the filter elements (104,106) and the second position is defined by a fluid storage reservoir (170).

Abstract: A rotary signal coupler for providing signal coupling to a Surface Acoustic Wave (SAW) device (4) mounted on a shaft (5) includes a first electrically conducting loop (21) mounted on a disc (23) and connected to the SAW device (4), and a second electrically conductive loop (22) mounted on a disc (24) and connected to external electronic circuitry. The disc (23) is fixed relative to the shaft (5) and the disc (24) is fixed relative to the structure in which the shaft (5) rotates so that the loops (21, 22) are inductively coupled. A grounded screen (27), which preferably takes the form of a plurality of radially extending fingers is located on the disc (23) and positioned between the loops (21, 22) to eliminate capacitive coupling therebetween.

Abstract: The invention includes an integrated adjustable resistor. The integrated adjustable resistor includes a first electrode, a second electrode, and a phase change medium electrically connected to the first electrode and the second electrode. The integrated adjustable resistor further includes an adjustable pulse generator for applying a variable amount of energy to the phase change medium. A resistance of the phase change medium is continuously dependent upon the amount of energy applied to the phase change medium. A resistance dependent circuit is electrically connected to the first electrode and the second electrode. Operation of the resistance dependent circuit is continuously dependent upon the resistance of the phase change medium.

Abstract: The invention provides a filter network comprising a plurality of circuit branches, each circuit branch comprising one or more filter elements. At least one of the circuit branches comprises a resonant circuit and is preferably arranged between the circuit path and ground. The filter network further comprises a switch device associated with the resonant circuit, the switch device being operable between an on state, in which the resonant circuit is connected to said circuit path, and an off state in which the resonant circuit is substantially isolated from said circuit path. The filter network also includes a switch control input for receiving a signal for operating the switch device between the on and off states. Switching in and out the resonant circuit changes the operational characteristics of the filter.

Abstract: A charge control circuit for controlling a micro-electromechanical system (MEMS) device having variable capacitor formed by first conductive plate and a second conductive plate separated by a variable gap distance. The charge control circuit comprises a switch circuit configured to receive a reference voltage having a selected voltage level and configured to respond to an enable signal having a duration at least as long as an electrical time constant constant of the MEMS device, but shorter than a mechanical time constant of the MEMS device, to apply the selected voltage level across the first and second plates for the duration to thereby cause a stored charge having a desired magnitude to accumulate on the variable capacitor, wherein the variable gap distance is a function of the magnitude of the stored charge.

Abstract: The invention relates to trimming of analogue filters (201) in integrated circuits by means of an automatic adjusting circuit. A local oscillator (202) in the automatic adjusting circuit provides a periodic reference signal (R) to an adjustable phase shifter (203), which on basis thereof, produces a periodic phase shifted signal (R*). A phase detector (204) receives both the periodic reference signal (R) and the phase shifted period signal (R*) and produces a test signal (T) in response to a phase difference between the periodic reference signal (R) and the periodic phase shifted signal (R8). A lowpass filter (205) receives the test signal (T) and generates a level signal (TDC) relative a reference level, e.g. representing a zero voltage. A digital signal processor (207) produces a primary control signal (CS), having a serial format, on basis of the observation signal (M). A serial-to-parallel converter (208) converts the primary control signal (CS) into a control signal (CP) having a parallel signal format.

Abstract: A tunable filter having a fixed substrate, a first and second plate comprising a high-temperature superconductor material on the fixed substrate, a movable substrate, a mechanical driver attached to the fixed substrate and the movable substrate, a floating plate comprising a high-temperature superconductor material on the fixed substrate wherein the floating plate, the first plate, and the second plate define a gap, and wherein the gap is varied by length changes in the mechanical driver is provided.

Abstract: A tuning circuit for use in an electrical circuit network is disclosed. The tuning circuit includes a bridge circuit. The bridge circuit comprises a first adjustable capacitance grouping, a second adjustable capacitance grouping and a third adjustable capacitance grouping. Each adjustable capacitance grouping includes at least one tunable capacitor and a bias port. In one embodiment, the tunable capacitor is comprised of a tunable thin-film barium strontium titanate (“BST”) capacitor. A first lead and a second lead couple to, or extend from, the bridge circuit. The leads are configured to couple with a coupling element and a shunt element of the electrical circuit network so that when the leads are grounded, one adjustable capacitance group is grounded and the remaining adjustable capacitance group couple with a bias voltage to appropriately tune the electrical circuit to achieve desired electrical characteristics.

Abstract: The bandpass filter has a comparatively large pass bandwidth, with, at the same time, comparatively steep edges up to the stop band and low attenuation in the passband. The bandpass filter contains three parallel LC elements, one of which is connected between the bandpass filter input and the bandpass filter output. The other two parallel LC elements each have one of their connections coupled to a fixed reference-ground potential.