Abstract: For example, in a conventional high frequency switch used for a mobile phone and so on, high frequency distortion is caused by a diode which is turned off upon transmission. A high frequency switch includes a switch circuit for switching transmission and reception performed via a transmitting terminal and receiving terminals, said switch circuit having a diode turned off upon transmission, and a low-pass filter for suppressing high frequency distortion caused by the diode upon transmission.

Abstract: The electrically tunable inductive device includes an electromagnet including an electromagnet core and a bias or tuning coil cooperating therewith to define opposing magnetic poles for generating a quiescent magnetic field that may be varied. An inductor is tunable based upon the variable magnetic field and includes an inductor core having a toroidal shape and fixed at a position adjacent the opposing magnetic poles of the electromagnet, and an inductor or signal coil is around at least a portion of the inductor core. The electromagnet core may include a pair of opposing legs and a bight portion therebetween defining a horseshoe shape. The inductor core may be positioned between ends of the opposing legs of the electromagnet core, and the tuning coil may surround the bight portion of the electromagnet core. The electrically tunable inductive device may have the combination of fine precision, high speed and high power handling, useful for tunable RF filters.

Abstract: A circuit and antenna arrangement includes a diplexer having a single radio frequency input/output interface and dual feed connections with an antenna adapted for use over a plurality of frequency bands. The diplexer has a capacitance connected between the radio frequency input/output interface and the antenna, and further has an additional capacitance that is selectively one of connected or not connected in parallel with the capacitance. In one embodiment the additional capacitance may be a capacitor in series with a switch, while in another embodiment the additional capacitance may be a MEMS variable capacitor.

Abstract: A digitally-tunable filter includes a tunable filter circuit (110) for generating an output signal by processing an input signal based at least on a plurality of filter control signals (114). The filter also includes an input power sampler (118) for sampling an input power of the input signal, an output power sampler (120) for sampling an output power of the output signal, and a tuning processor (112) for generating the plurality of filter control signals based on at least one channel control signal (116) associated with a current communications channel and a comparison of the input and the output powers. In the filter, the plurality of control signals configure the tunable filter circuit to attenuate at least a portion of the input signal if a difference between the input power and the output power is less than a threshold value.

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: A second operational amplifier (7) is arranged, as an interface circuit (6), between a first operational amplifier (5) outputting the control voltage (Vcd) of a dummy filter (2) and a main filter (1), and the reference voltage (Vr) of the second operational amplifier (7) is optimized such that the control voltage (Vcd) obtained by using the dummy filter (2) is converted through the interface circuit (6) into a control voltage (Vcm) most suitable for the main filter (1), thereby obtaining a control voltage (Vcm) most suitable for regulating the frequency characteristics of the main filter (1) to desired characteristics.

Abstract: A tuning method and circuit for an LC tank resonant circuit, including an inductor and a variable capacitor, are described. In a tuning mode, an RF input signal is applied to an input port of the circuit, and the RF output signal is monitored as a variable capacitor control input is varied. A peak output is detected, and the corresponding variable capacitor control input is stored, and applied to the variable capacitor in an operating mode. In one embodiment, the variable capacitor control input is adjusted for delay in the peak detection process. In one embodiment, the variable capacitor comprises a coarse capacitor and a fine capacitor; the tuning procedure is repeated for each capacitor; and both coarse and fine variable capacitor control inputs are stored and applied to the respective capacitors in operating mode.

Abstract: One embodiment of the invention relates to a dynamically adjustable differential band-pass filter. This band-pass filter includes a first leg that has an input portion and an output portion with a first inductor therebetween. It also includes a second leg in parallel with the first leg, where the second leg has an input portion and an output portion with a second inductor therebetween. The first inductor is symmetrically inter-woven with the second inductor. In some embodiments, the band pass filter is configured to compensate for losses due to the inductors. Other band-pass filters and methods are also disclosed.

Abstract: A high frequency filter includes: an input terminal; an output terminal; and a variable capacitance circuit provided between the input terminal and the output terminal or between a ground and one of the input terminal and the output terminal, and formed on the semiconductor substrate including a capacitor and a switch element. The switch element is connected in series with the capacitor.

Abstract: A switched capacitor is characterized in that it comprises a series MEMS-type switch, the capacitor to be switched being integrated into the structure of the MEMS switch and being formed by an additional metal layer produced on part of the dielectric layer of the MEMS switch, the capacitance of the switched capacitor being set as a function of the area of the metal layer.

Abstract: A passive switched-capacitor (PSC) filter includes (i) an array of capacitors that can store and share electrical charge and (ii) an array of switches that can couple the capacitors to a summing node. Each switch couples an associated capacitor to the summing node when enabled. Each capacitor stores a voltage value from the summing node when selected for charging and shares electrical charge with other capacitors via the summing node when selected for charge sharing. The PSC filter may include multiple sections for multiple filter taps. Each section includes one or more capacitors of equal size determined based on a corresponding filter coefficient. The capacitors in each section may be sequentially selected for charging with an input or output signal, one capacitor in each clock cycle. In each clock cycle, one capacitor in each section may be selected for charge sharing to generate the output signal.

Abstract: A digital to analog converter for converting a digital input signal provided by a host to an analog output signal includes a modulator receiving the digital input signal, modulating the digital input signal, and outputting a modulated signal, and a filtering circuit receiving the modulated signal, low pass filtering the modulated signal, and outputting the analog output signal to an output node. The filtering circuit includes a first switching circuit for adjusting the bandwidth of the filtering circuit according to a bandwidth switching signal.

Abstract: A noise measurement system in power stabilization network, a variable filter applied to the same and a method for measuring noise in power stabilization network are disclosed, wherein the system comprises: a power stabilization network including a power input unit for receiving an external power, a power output unit for supplying a power to a power line communication modem and an output unit for a measurement instrument; a filter connected to the power stabilization network; and an EMI (Electromagnetic Interference) measurer.

Abstract: A controllable filter arrangement with a voltage controlled device that subjects a signal to a predetermined impedance as part of the filtering process when the voltage controlled device is in an active state. In an inactive state, the voltage controlled device may subject the signal to an impedance that prevents all frequencies of the signal from passing. This configuration may advantageously increase frequency selectivity and reduce insertion loss, size, cost, and tuning complexity when compared with conventional filter designs.

Abstract: A wideband variable frequency band pass filter of an IEEE 802.22 wireless regional area network (WRAN) system operating in a very high frequency (VHF)/ultra high frequency (UHF) TV broadcast band.

Abstract: There is provided a filter circuit that includes: a flying capacitor which maintains polarity when switching from an input terminal to an output terminal, and the polarity of which is reversed when switching from the output terminal to the input terminal; a first capacitor that is provided in parallel to the flying capacitor, at the input terminal of the flying capacitor; and a second capacitor that is provided in parallel to the flying capacitor, at the output terminal of the flying capacitor. The flying capacitor includes a variable capacity element such that capacity becomes smaller when switching from the input terminal to the output terminal and capacity becomes larger when switching from the output terminal to the input terminal.

Abstract: An 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: An electronic filter (100) comprising: a filter section (102, 104); an impedance correction section (106 and 108) that is electrically coupled to the filter section (102, 104); and a circuit altering section (110-116) that is arranged to alter at least one property of the impedance correction section (106, 108) to effect a shift in a resonant frequency of the impedance correction section (106, 108) from with a pass band of the filter section to within a stop band of the filter section (102, 104).

Abstract: A voltage-controlled capacitor and methods for forming the same are described. A mechanical conductor membrane of the voltage-controlled capacitor is movable to and from a first position and a second position. An amount of capacitance can vary with the movement of the mechanical conductor membrane. A microelectromechanical systems (MEMS) voltage-controlled capacitor can be used in a variety of applications, such as, but not limited to, RF switches and RF attenuators.

Abstract: A channel-select decimation filter capable of operating in multiple bandwidth modes includes a first low pass filter stage, a variable gain stage, a subtraction module a second low pass filter stage and a down-sampling module. The first low pass filter stage includes a first programmable delay module for filtering input signals to produce first low pass filtered signals. The variable gain stage applies a programmable gain to the input signals to produce gained input signals. The subtraction module subtracts the first low pass filtered signals from the gain input signals to produce first stage signals. The second low pass filter stage includes a second programmable delay module for filtering the first stage signals to produce channel-selected signals. The first programmable delay module, second programmable delay module and programmable gain are programmed to implement one of the multiple bandwidth modes.

Abstract: An apparatus includes first and second filters and a bandwidth control circuit. The first filter operates as part of a first oscillator in a first mode and filters a first input signal and provides a first output signal in a second mode. The second filter operates as part of a second oscillator in the first mode and filters a second input signal and provides a second output signal in the second mode. The bandwidth control circuit adjusts the bandwidth of the first and second filters in the first mode, e.g., adjusts the oscillation frequency of each oscillator to obtain a target bandwidth for an associated filter. The apparatus may further include first and second gain control circuits. Each gain control circuit may vary the amplitude of an oscillator signal from an associated oscillator and/or set a gain of an associated filter in the first mode.

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 radio transceiver device includes circuitry for radiating electromagnetic signals at a very high radio frequency both through space, as well as through wave guides that are formed within a substrate material. In one embodiment, the substrate comprises a dielectric substrate formed within a board, for example, a printed circuit board. In another embodiment of the invention, the wave guide is formed within a die of an integrated circuit radio transceiver. A plurality of transceivers with different functionality is defined. Substrate transceivers are operable to transmit through the wave guides, while local transceivers are operable to produce very short range wireless transmissions through space. A third and final transceiver is a typical wireless transceiver for communication with remote (non-local to the device) transceivers. Additionally, a multi-mode transceiver is operable to configure transmit and receive circuitry based upon transmission path.

Abstract: An agile frequency converter provides IF-RF level exchange and notch filtering. System noise and spurious levels generated by channel frequency conversion is reduced in applications requiring broadband combining of frequency converters to form multichannel composite signal. A pair of varactor banks is connected in an arrangement whereby varactor pairs are connected in parallel and capacitor pairs are connected in anti-parallel. Tuning is achieved by circuitry for tuning first and second varactors.

Abstract: Various embodiments include apparatus, systems, and methods having a conductive contact configured to couple to a resistor-capacitor (RC) network, a device unit coupled to the conductive contact, and a mode switching unit to change a characteristic of a signal at the conductive contact based at least in part on an RC time constant of the RC network. The mode switching unit may switch the device unit between a first operating mode and a second operating mode based on a signal level of the signal.

Abstract: One embodiment relates to a circuit for active loss compensation. The circuit includes a parallel inductor-capacitive (LC) tank circuit having a first single-ended output. A first adjustable capacitor, which includes a first terminal and a second terminal, is coupled to the first single-ended output. The circuit also includes a first pair of transistors having sources coupled to a first common node. One transistor of the first pair of transistors has a drain coupled to the first single-ended output and the other transistor of the first pair of transistors has a gate coupled to the second terminal of the first adjustable capacitor. Other embodiments are also disclosed.

Abstract: A high frequency filter includes an inductor, a serial resonance circuit including an inductor and capacitors, a serial resonance circuit including an inductor and capacitors, and a varactor diode connected between a connection point between the capacitor and the capacitor and a connection point between the capacitor and the capacitor. A controller simultaneously changes two attenuation pole frequencies of the filter device by changing a capacitance of the varactor diode.

Abstract: A method is provided for controlling a resonant circuit (1) of an ICPT system. The resonant circuit has a controlled variable reactance (2), and a predetermined perturbation is introduced in the magnitude of variable reactance. The change in a property of the resonant circuit in response to the perturbation is sensed, and the variable reactance is varied to alter the resonant frequency of the circuit in response to the sensed change.

Abstract: According to one exemplary embodiment, a selectable notch filter includes a transmission line, a bias circuit, and a switch for selectably coupling the transmission line to ground. In one embodiment, the switch is a PIN diode. The selectable notch filter can selectably suppress a first frequency from being output when the transmission line is coupled to ground. Additionally, the selectable notch filter can selectably suppress a second frequency from being output when the transmission line is not coupled to ground. In one embodiment, the first frequency is approximately equal to a multiple of two of the second frequency. In one embodiment, the selectable notch filter can utilize more than one transmission line.

Abstract: A series resonance circuit defined by a series circuit including an inductor and a capacitor and a series resonance circuit defined by a series circuit including an inductor and a capacitor are connected in shunt to a signal line. A diode is disposed between the grounding end of the series resonance circuit and the ground, and a diode is disposed between the grounding end of the series resonance circuit and the ground. The connection point between the grounding end of the series resonance circuit and the diode is connected to the ground via a frequency shifting inductor in a conductive state at high frequency, and the connection point between the grounding end of the series resonance circuit and the diode is connected to the ground via a frequency shifting inductor in a conductive state at high frequency. A matching circuit defined by a multistage T-shape LCL circuit is disposed between the series resonance circuits.

Abstract: A method and apparatus for dynamically varying the impedance of a tank circuit whereby, over time, the response of the circuit to a received signal is maximized.

Abstract: A filter circuit includes first capacitors, second capacitors capable of altering a cutoff frequency by being connected in parallel with the first capacitors, first switches for connecting the second capacitors in parallel with the first capacitors, and charging circuits for the second capacitors. The charging circuits include second switches, and resistances for attenuating the amplitudes of input voltages to be fed to the second capacitors, by being connected in series with the second capacitors. The second capacitors are charged through the resistances in a state where the first switches are turned OFF and where the second switches are turned ON. Thus, a DC offset which is ascribable to the cutoff frequency switching of a filter is reduced.

Abstract: An integrated variable inductor is achieved by placing a second closed-loop inductor immediately above or below a primary inductor. The closed-loop configuration of the second inductor may be broken on-chip by several ways, including use of a transistor to selectively short together both ends of the second inductor. If one wishes to alter the inherent inductance characteristics of the primary inductor, the transistor coupling both ends of the second inductor is actuated. Thus, a current applied to the primary inductor induces a current in the second inductor by inductive coupling. The second current in the second inductor then alters the impedance of the primary inductor by mutual inductance. Thus, the inductance value of the primary inductor is altered. To remove the influence of the second inductor on the primary inductor, the closed-loop configuration of the second inductor is broken.

Abstract: According to one exemplary embodiment, a selectable notch filter includes a transmission line, a bias circuit, and a switch for selectably coupling the transmission line to ground. In one embodiment, the switch is a PIN diode. The selectable notch filter can selectably suppress a first frequency from being output when the transmission line is coupled to ground. Additionally, the selectable notch filter can selectably suppress a second frequency from being output when the transmission line is not coupled to ground. In one embodiment, the first frequency is approximately equal to a multiple of two of the second frequency. In one embodiment, the selectable notch filter can utilize more than one transmission line.

Abstract: A method and apparatus for dynamically varying the impedance of a tank circuit whereby, over time, the response of the circuit to a received signal is maximized.

Abstract: An inductor and method of operating the inductor by combining primary and secondary coils with passive coupling, active parallel, or active cross-coupling structures. The first includes at least one passive coupling structure having at least one coupling coil arranged between a primary coil and at least one of the secondary coils and/or between two of the secondary coils. The second includes an active coupling structure arranged between a primary coil and at least one secondary coil and/or between at least two of the secondary coils, to selectively parallel couple the primary coil and one of the secondary coils and/or at least two of the secondary coils. The third includes an active coupling structure to selectively cross couple a primary coil and at least one of the secondary coils and/or to selectively cross couple at least two of the secondary coils.

Abstract: The invention relates to a small and low-voltage operable dielectric waveguide device. First and second electrode are embedded in a dielectric part and are formed to be thinner than a skin depth for a frequency of electromagnetic wave propagating along a first dielectric part included in the dielectric part. Thereby, even if the first and second electrodes are arranged to be in contact with the first dielectric part, the propagating electromagnetic wave can transmit the first and second electrodes, and therefore the electromagnetic wave can propagate without being cut off and there is no influence on waveguide modes of the electromagnetic wave. Further, in a state where a transmission loss due to the embedded of the electrode is suppressed, an electric field with large electric field strength can be applied to the first dielectric part by the first and second electrodes, and a small and low-voltage operable dielectric waveguide device can be achieved.

Abstract: The electrically tunable inductive device includes an electromagnet including an electromagnet core and a bias or tuning coil cooperating therewith to define opposing magnetic poles for generating a quiescent magnetic field that may be varied. An inductor is tunable based upon the variable magnetic field and includes an inductor core having a toroidal shape and fixed at a position adjacent the opposing magnetic poles of the electromagnet, and an inductor or signal coil is around at least a portion of the inductor core. The electromagnet core may include a pair of opposing legs and a bight portion therebetween defining a horseshoe shape. The inductor core may be positioned between ends of the opposing legs of the electromagnet core, and the tuning coil may surround the bight portion of the electromagnet core. The electrically tunable inductive device may have the combination of fine precision, high speed and high power handling, useful for tunable RF filters.

Abstract: (Problem) To provide a charge sampling filter circuit and a charge sampling method. (Means for Resolution) A charge sampling filter circuit includes a first capacitor that samples an input signal, and in which at least a portion of electric charge stored in the first capacitor by sampling is output to a second capacitor that is connectable with the first capacitor. The charge sampling filter circuit is characterized by including a switching portion that switches a circuit mode including a sampling mode that causes the first capacitor to sample the input signal, and an output mode that causes the first capacitor and the second capacitor to be connected. A capacitance value of the first capacitor in the output mode is set to be lower than the capacitance value in the sampling mode.

Abstract: The present invention reduces distortion in variable capacitance devices by connecting a circuit to the variable capacitance devices that has low impedance at predetermined frequencies to suppress those frequencies and also suppress harmonics and mixing products resulting from mixing of various frequencies.

Abstract: In a signal communication device, a frequency-selective filter has at least one component that is biased by a control signal to establish a center frequency of the frequency-selective filter. A closed-loop bias generator is provided to generate the control signal and to adjust the control signal based, at least in part, on a comparison of the control signal and a reference signal.

Abstract: A charge domain filter circuit includes a first signal output portion, at least one second signal output, portion, a third signal output portion, and an adder portion. The first signal output portion outputs a first signal that is sampled at a specified time interval. Each second signal, output portion outputs a second signal that is sampled after a specified delay after the first signal is sampled. Where a plurality of the second signal output portions is included, the second signals are sampled in succession. The third signal output portion outputs a third signal that is sampled after a specified delay after the last second signal is sampled. The adder portion adds the first, second, and third signals together and outputs the result. The capacitance ratio of the sampling capacitors in the first signal output portion and the second signal output portion is one of continuously or discretely varied.

Abstract: One embodiment of the invention relates to a dynamically adjustable differential band-pass filter. This band-pass filter includes a first leg that has an input portion and an output portion with a first inductor therebetween. It also includes a second leg in parallel with the first leg, where the second leg has an input portion and an output portion with a second inductor therebetween. The first inductor is symmetrically inter-woven with the second inductor. In some embodiments, the band pass filter is configured to compensate for losses due to the inductors. Other band-pass filters and methods are also disclosed.

Abstract: A second operational amplifier (7) is arranged, as an interface circuit (6), between a first operational amplifier (5) outputting the control voltage (Vcd) of a dummy filter (2) and a main filter (1), and the reference voltage (Vr) of the second operational amplifier (7) is optimized such that the control voltage (Vcd) obtained by using the dummy filter (2) is converted through the interface circuit (6) into a control voltage (Vcm) most suitable for the main filter (1), thereby obtaining a control voltage (Vcm) most suitable for regulating the frequency characteristics of the main filter (1) to desired characteristics.

Abstract: A noise filter array includes filter elements including an LC parallel resonant circuit and an LC series resonant circuit each of which includes a coil and a capacitor provided in proximity in an array and integrally provided with one another. The LC series resonant circuits include ground capacitors having signal-side electrodes. Inductance adjustment conductors are connected to signal-side electrodes of the capacitors defining the respective filter elements, and a ground electrode of the capacitors is commonly arranged so as to oppose the signal-side electrodes.

Abstract: An integrated balun includes a low pass filter and a high pass filter that are formed on a semiconductor chip using tunable reactive elements. The outputs of the low pass filter and the high pass filter are tied together to form the single ended output of the balun. The inputs of the low pass filter and the high pass filter form the differential inputs of the balun. The low pass filter and the high pass filter each include a number of tunable networks for achieving the tunable reactive elements. Each tunable network includes at least one switching transistor and at least one fixed value reactive elements. In at least one embodiment, dynamic biasing circuitry may be provided to improve the linearity and reduce the insertion loss of the balun.

Abstract: An integrated, multi-band radio frequency (RF) filter is capable of modifying a filter response thereof in response to control information. Switching elements within the filter can be changed between on and off conditions to modify the filter response. In one implementation, the integrated, multi-band filter is integrated on a front end module chip to be used within a multi-radio wireless device. In at least one embodiment, linearity enhancement circuitry is provided within a multi-band filter to improve linearity and reduce insertion loss.

Abstract: Two second-order bandpass filter are connected serially to obtain a dual bandpass filter. One is inductive and the other is capacitive. One has a low passband and the other has a high passband. Between them, a finite transmission zero is formed to suppress noise. The present invention achieves a passband as wide as 1 gigahertz so that it can be applied to a wireless local network, communication equipments and electronic devices.

Abstract: An 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: An integrated capacitor and inductor device for separate use as a capacitor and inductor. The device has a four-terminal arrangement having separate capacitor and inductor terminals, which allows connection as two independent circuit elements within one physical package. The device includes a hollow vessel having an exposed integrated capacitor element, in which the exposed integrated capacitor element comprises at least a portion of the hollow vessel. The device also includes a coil winding at least partially within the hollow vessel, electrically communicating with the integrated capacitor element. The integrated capacitor and inductor device may be configured in a plurality of shapes, using different materials to maximize the effects of electric and magnetic fields.