Abstract: An automatically tuned on-chip active continuous-time real bandpass filter operates on a differential signal while simultaneously being tuned using a common-mode (CM) reference signal, which results in a superior accuracy of its center frequency and bandwidth. The filter consists of two or more pairs of gm-C or other types active resonators that can be single-ended or differential. The two identical filters are tuned with CM reference that is rejected at the output of each pair of resonators. For each pair of resonators, the present frequency-tuning finds the resonant frequency, for which the bandpass (BP) and lowpass magnitude values are equal. For each pair of resonators, the present Q-tuning scheme adjusts BP magnitude at the resonant frequency and its Q to the appropriate value. The present tuning method allows building a reasonably flat passband BP filter using two or more pairs of resonators.

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 filtering apparatus includes a main filter, a variation detection circuit, and a variation correction circuit. The variation detection circuit includes a reference filter having at least one resistor and at least one capacitor, detects a variation of CR-product based on the resistor and the capacitor of the reference filter in response to each of a plurality of reference signals having different frequencies from each other, and then outputs a variation detection signal indicating a detected result. The variation correction circuit corrects frequency characteristics of the main filter on the basis of the variation detection signal.

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

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: Devices having setting elements are adjusted by carrying out a first measurement of a characteristic curve to be controlled at predefined measurement points, each setting element assuming a reference setting; testing a termination condition and terminating the method if this condition is satisfied; and, if the termination condition is not satisfied, modifying the reference setting of each setting element and measuring the characteristic curve again at predefined measurement points for this configuration; reproducing the initial reference setting of the modified setting element; when there is more than one setting element, calculating the gradient functions of the characteristic curve; calculating new settings by minimizing an error function by using the obtained measured values and the calculated gradient functions; and carrying out the method again, beginning with the new calculated settings serving as the new reference setting.

Abstract: Equalizing a signal includes receiving a data sequence signal having an amplitude. An adjustment of the data sequence signal operable to equalize the data sequence signal is determined. A control signal operable to adjust the amplitude of the data sequence signal in accordance with the adjustment is generated, where the control signal has an analog form. The amplitude of the data sequence signal is adjusted using the control signal in order to equalize the data sequence signal.

Abstract: An antenna system is disclosed, to be used with a radio component particularly a wireless access point or bridge. The present system includes an antenna element for transmitting and receiving signals at radio frequencies. An antenna connector is provided for establishing a signal connection between the antenna element and a radio component. An electronic serialization component is provided for indicating one or more predetermined antenna characteristics. This component is adapted to read out the predetermined antenna characteristics through the antenna connector to the radio component.

Abstract: A tunable filter has a plurality of variable capacitors and a plurality of inductor elements, each being formed on a common substrate, a filter circuit formed by using at least a portion of the plurality of variable capacitors and a portion of the plurality of inductor elements, a monitor circuit formed by using at least a portion of the plurality of variable capacitors and a portion of the plurality of inductor elements, a detecting circuit which detects a prescribed circuit constant of the monitor circuit, a storage which stores information relating to a reference circuit constant of the monitor circuit, and a capacitance control circuit which controls capacitance of the variable capacitors in the monitor circuit and capacitance of the variable capacitors in the filter circuit, based on a result detected by the detecting circuit and information stored in the storage.

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 mechanically balanced automatic microwave tuner is used in on-wafer device testing. Using low loss rigid airlines to connect the tuner and the devices improves the tuning range at the DUT reference plane but causes mechanical movements of the wafer probes, when the tuner mobile carriage moves horizontally. Balancing the tuner by means of exactly positioned and dimensioned mobile counterweights, driven by the same mechanism as the tuner carriage itself, allows for compensation of the probe movement and safe on wafer operation.

Abstract: An automatic antenna-switching apparatus is provided for the user to connect a single multiband communications platform to a group of antennas with different frequencies by detecting the RF energy input representing the user's selected frequency and automatically switching to the properly polarized and matched antenna for the intended radio band in the group of antennas. The automatic antenna-switching apparatus includes an RF input port, a means for RF sensing, a means for antenna port selection, a group of RF output connectors and a group of different output antennas. The RF sensing means senses the RF energy with a means for frequency counting that determines the exact frequency represented by the RF energy during a particular radio transmission. The RF sensing means sends a frequency count output to the antenna port selection means that compares the frequency count output with the available connected output antennas.

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: The present invention relates to a method for tuning a radio filter. The filter comprises an input connection, an output connection and at least two resonator modules coupled in cascade, each having a tuning mechanism and a probe. A first resonator module is connected to the input connection and a final resonator module is connected to the output connection. The filter is adapted to receive at least one signal within a frequency range. The method comprises essentially two steps: coarse tuning, which is dependent on the frequency content of the received signal(s), and fine tuning, which is dependent on a calculated deviation between a set value vector and a measured signal parameter vector. A relationship between the set value vector and the signal parameter vector is established for calculating the deviation. The invention also relates to a radio filter and a system comprising such a radio filter.

Abstract: An automatic tuning system for a magnetic field generating tuned circuit includes a processor configured to maintain the resonant frequency of a tuned circuit equal to a reference frequency. The tuned circuit is driven by a power amplifier whose output provides an amplified signal at the reference frequency. The tuned circuit includes a magnetic field generating inductor and a bank of individually switchable capacitors controlled by the processor capable of adding and removing the respective capacitances to and from the tuned circuit. The inductor includes a Faraday shield to shield the tuned circuit from the influence of electric fields. A power sense circuit monitors the power delivered by the power amplifier to the tuned circuit and the processor sequentially switches the capacitors in a binary progression format to achieve maximum power delivery indicative of conforming the resonant frequency of the tuned circuit to the reference frequency.

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: A receiver capable of reducing the number of pads of a semiconductor device used for connection with a tuning circuit. The receiver includes a semiconductor device 100 containing various circuits and a tuning circuit 130 connected as a separate part to this semiconductor device 100. The semiconductor device 100 has a pad 112 formed on a semiconductor substrate 110, a processing circuit 114 connected via a capacitor 120 to the pad 112, and a D/A converter 122 connected via a resistor 124 to the pad 112. A tuning voltage generated by the D/A converter 122 is applied via the pad 112 to the tuning circuit 130. Moreover, an output signal of the tuning circuit 130 is supplied to the pad 112 and fed via the capacitor 120 to the processing circuit 114.

Abstract: The present invention relates to a method for tuning a radio filter. The filter comprises an input connection, an output connection and at least two resonator modules coupled in cascade, each having a running mechanism and a probe. A first resonator module is connected to the input connection and a final resonator module is connected to the output connection. The filter is adapted to receive at least one signal within a frequency range. The method comprises essentially two steps: coarse tuning, which is dependent on the frequency content of the received signal(s), and fine tuning, which is dependent on a calculated deviation between a set value vector and a measured signal parameter vector. A relationship between the set value vector and the signal parameter vector is established for calculating the deviation. The invention also relates to a radio filter and a system comprising such a radio filter.

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: 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: An automatic tuning scheme for two active band-pass filters where both filters operate on the signal while simultaneously being tuned using a reference signal. To allow that the amplitude of a reference signal is made small and since both filters demonstrate a good linearity the build-up of the inter-modulation distortion does not occur. The first band-pass filter is tuned with the reference falling into its pass-band. The second band-pass filter is also tuned with the reference placed into its pass-band. The reference is practically eliminated by the virtue of the complexity of the second band-pass filter. Assuming the filter passes the signal for positive frequencies if the reference is made a negative frequency by appropriate 90 degrees phase shifting it will be attenuated by at least 55 dB, which is a sufficient signal-to-reference ratio.

Abstract: An automatic tuning scheme for two active band-pass filters where both filters operate on the signal while simultaneously being tuned using a reference signal. To allow that the amplitude of a reference signal is made small and since both filters demonstrate a good linearity the build-up of the inter-modulation distortion does not occur. The first band-pass filter is tuned with the reference falling into its pass-band. The second band-pass filter is also tuned with the reference placed into its pass-band. The reference is practically eliminated by the virtue of the complexity of the second band-pass filter. Assuming the filter passes the signal for positive frequencies if the reference is made a negative frequency by appropriate 90 degrees phase shifting it will be attenuated by at least 55 dB, which is a sufficient signal-to-reference ratio.

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: 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 tuneable filter, for example an antenna filter in a single chip radio receiver, comprises a frequency selective circuit (12) including passive reactive components. At least some of the reactive components (48 to 52) are arranged as a bank (46 ) which includes switches (53 to 57) for switching at least one of the reactive components in the bank into the frequency selective circuit. A controller controls the switching means to select the or a combination of the reactive components which provides an optimum sensitivity for an input signal at a first frequency. The switch settings required to optimise the sensitivity for other frequencies is determined by measuring the decrease in sensitivity for other switch settings, with the input signal still at the first frequency, and using stored data about the shape of the frequency response of the tuneable filter.

Abstract: A method for tuning a cavity filter is provided. The cavity filter includes a plurality of tuning members. The method includes selecting a stored set of positional values for the tuning members, driving the tuning members of the cavity filter to the stored set of positional values, and further adjusting the position of the tuning members as necessary to achieve a desired frequency response for the cavity filter.

Abstract: A method for tuning a high quality resonant circuit based on bonding wire inductors and tunable capacitors is disclosed which permits greater integration on standard silicon chips and greater insensitivity to manufacturing and ambient temperature variations. The L-C resonant circuit is tuned by a phase-locked loop with an L-C based VCO. Bonding wire inductors can be used in the resonant circuit in order to enhance the quality factor, and manufacturing variations of the bonding wire inductors are compensated by the tuning circuit. The L-C resonant circuit can be operated continuously with the tuning circuit turned off.

Abstract: An apparatus and method for filtering a signal in a phase lock loop is disclosed. An typical apparatus for filtering a phase error signal comprises a first filter subcircuit receiving a phase error signal from a phase comparator and filtering the error signal when enabled, a second filter subcircuit receiving the phase error signal from the phase comparator and filtering the error signal when enabled and first and second enable switches which are activated in combination to control filtering of at the error signal. The first filter subcircuit is enabled by activating a first combination of the enable switches and the second filter subcircuit is enabled by activating a second combination of the enable switches. A fast acquisition subcircuit can also be used to temporarily underdampen the filter and improve overall performance of the phase lock loop circuit. The filter can be used to obtain multimode operation in a cellular radio.

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 microelectromechanical system (MEMS) analog isolator may be created in which an actuator such as an electrostatic motor drives a beam against an opposing force set, for example, by another electrostatic motor. Motion of the beam may be sensed by a sensor also attached to the beam. The beam itself is electrically isolated between the locations of the actuator and the sensor. The structure may be incorporated into integrated circuits to provide on-chip isolation.

Abstract: A device and method for tuning a planar filter through a wide range of center frequencies are disclosed. The tuning assembly includes a superconductive tuning tip and an actuator configured and adapted to move the tuning tip through a sufficient range of distances from a resonator or a portion thereof to vary the resonant frequency of the resonator by at least about 10% of the untuned frequency in at least one increment of 0.01% or smaller. An actuator and a position-sensor can be employed in a closed loop feedback system to control the position of the tuning tips. The present invention also provides a method of tuning a filter that includes moving a tuning tip through a sufficient range of distances from a resonator to vary the resonant frequency of the resonator by at least about 10% in at least one increment of 0.01% or smaller.

Abstract: The invention relates to a tuning circuit for tuning a filter stage, which has an RC element (1) with an RC time constant (&tgr;), with the RC time constant (&tgr;) being the product of the resistance of a resistor (R1) in the RC element (1) and the capacitance of a capacitor (C1), which is connected in series with the resistor (R1), in the RC element (1), having a comparator (10) for comparison of the voltage which is produced at the potential node (4) between the resistor (R1) and the capacitor (C1), with a reference ground voltage; and having a controller (15) which varies the charge on the capacitor (C1) in the RC element (1) until the comparator (10) indicates that the voltage which is produced at the potential node (4) is equal to the reference ground voltage, with the controller (15) switching a capacitor array (26) as a function of the charge variation time, which capacitor array (26) is connected in parallel with the capacitor (C1) in the RC element (1), in order to compensate for any discrepancy bet

Abstract: An apparatus and method for tuning a filter (11) with oscillator alignment for applications where the filter tuning signal (19, 27) is generated independently of the local oscillator tuning signal and the tuning range is large, for example such as terrestrial and cable TV broadcasting (40 to 860 MHz). The filter being adapted to a filter tuning modulation signal (25) having a first frequency (F1) and a second frequency (F2). Values of the output signal (28) are measured, a first value (S1) at the first frequency, and a second value (S2) at the second frequency, and a comparison signal (26) is generated in comparing the first value and the second value to adjust filter with the tuning control signal in response to the comparison signal, modulation signal and an approximate filter tuning signal to provide a desired signal at the output signal.

Abstract: A bandpass filter is tuned by converting the filter into an oscillator using a negative resistance circuit, tuning the oscillator by using conventional tuning techniques such as tuning a varactor via a phase locked loop, sampling and holding the tuning signal and switching off the negative resistance circuit to convert the oscillator back into a bandpass filter.

Abstract: A method for damping an LC filter coupled to a converter and generating a filter signal. The method comprises sensing the filter signal and processing the filter signal to generate a corresponding feedback signal. The feedback signal is subtracted from a controller signal to generate a difference signal. The difference signal is used for damping the LC filter.

Abstract: A high-frequency filter device includes at least one filter to be connected to a high-frequency stage of a wireless apparatus. The filter includes a voltage-controlled variable frequency resonance element which is made of a resonance element and a voltage-controlled variable impedance element electrically connected to the resonance element. The high-frequency filter device includes a control section for controlling a voltage applied to the variable impedance element, and a signal monitoring section for outputting a control signal, with which the voltage is controlled, to the control section based on frequency data as to an oscillating frequency of a local oscillator of the wireless apparatus. The signal monitoring section controls a band frequency of the at least one filter based on the frequency data in such a manner that the band frequency is adaptively changed.

Abstract: A receiver, such as a television receiver, tunes an inductive (“L”) and capacitive (“C”) filter based on a desired frequency. The LC filter includes a plurality of inductors, configured in at least one inductive (“L”) bank, and a plurality of capacitors configured in at least one capacitive (“C”) bank. The inductors are selectively enabled for the LC filter by an N code, and the capacitors are selectively enabled for the LC filter by an M code. The receiver uses a functional comparator to compare offset, capacitive, inductive and frequency values to tune the LC filter. Techniques for tuning the LC filter for operation in the VHF and UHF bands are disclosed.

Abstract: The present invention tunes a coupled resonator filter to a given tuning specification using a reference filter that was previously tuned to the specification. A method of tuning a subject filter comprises determining a frequency change for each resonator of the subject filter and applying each determined change to the respective resonator, such that the subject filter is tuned to the specification. The frequency changes are determined from frequency-pushing interactions between combinations of resonators in either the reference or subject filter. A system for tuning the subject filter comprises a measurement system, a tuning program stored in a system memory, and a controller that controls the measurement system and executes the tuning program. The tuning program comprises instructions that preferably implement the tuning method. A tuned coupled resonator filter comprises a plurality of resonators that are adjusted in accordance with the method or using the tuning system.

Abstract: Single and multiple ferrite crystal resonator, oscillator, and filter coupling structures are disclosed. In one embodiment, a single ferrite crystal resonator coupling structure is configured as a single pole YIG-tuned-oscillator (YTO) coupling structure. The YTO coupling structure includes a circuit substrate having an upper and a lower side. The circuit substrate includes an aperture extending through the circuit substrate between first and second openings on the upper and lower sides, respectively. The aperture is configured to permit rotation of a ferrite crystal disposable at least partially therein about a plurality of axes whereby a desirable axis of the ferrite crystal is alignable with a magnetic field within the aperture. At least one coupling line through which an electric current can be directed, which extends between a first end and a second end of the first opening of the aperture across at least a portion of the first opening of the aperture.

Abstract: The present invention relates to a method for tuning a radio filter. The filter comprises an input connection, an output connection and at least two resonator modules coupled in cascade, each having a running mechanism and a probe. A first resonator module is connected to the input connection and a final resonator module is connected to the output connection. The filter is adapted to receive at least one signal within a frequency range. The method comprises essentially two steps: coarse tuning, which is dependent on the frequency content of the received signal(s), and fine tuning, which is dependent on a calculated deviation between a set value vector and a measured signal parameter vector. A relationship between the set value vector and the signal parameter vector is established for calculating the deviation. The invention also relates to a radio filter and a system comprising such a radio filter.

Abstract: A method for damping an LC filter coupled to a converter and generating a filter signal. The method comprises sensing the filter signal and processing the filter signal to generate a corresponding feedback signal. The feedback signal is subtracted from a controller signal to generate a difference signal. The difference signal is used for damping the LC filter.

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: An RF signals amplification block receives a first RF signal (RFin), and comprises means of amplification (3, 4, 12, 15) of this first RF signal so as to deliver a second, amplified, RF signal (RF1). This signal (RF1) must be amplified by a predetermined nominal power (Pout) so as to be delivered at the output of the block.

Abstract: A tunable resonator is provided. The resonator includes a housing having a cavity. A resonator body is disposed adjacent to a first surface within the cavity. A gap is formed between the resonator body and the first surface. The resonator is tuned by controlling the size of the gap.

Abstract: A receiver, such as a television receiver, tunes an inductive (“L”) and capacitive (“C”) filter based on a desired frequency. The LC filter includes a plurality of inductors, configured in at least one inductive (“L”) bank, and a plurality of capacitors configured in at least one capacitive (“C”) bank. The inductors are selectively enabled for the LC filter by an N code, and the capacitors are selectively enabled for the LC filter by an M code. The receiver uses a functional comparator to compare offset, capacitive, inductive and frequency values to tune the LC filter. Techniques for tuning the LC filter for operation in the VHF and UHF bands are disclosed.

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: A high-frequency filter device includes at least one filter to be connected to a high-frequency stage of a wireless apparatus. The filter includes a voltage-controlled variable frequency resonance element which is made of a resonance element and a voltage-controlled variable impedance element electrically connected to the resonance element. The high-frequency filter device includes a control section for controlling a voltage applied to the variable impedance element, and a signal monitoring section for outputting a control signal, with which the voltage is controlled, to the control section based on frequency data as to an oscillating frequency of a local oscillator of the wireless apparatus. The signal monitoring section controls a band frequency of the at least one filter based on the frequency data in such a manner that the band frequency is adaptively changed.