Abstract: Embodiments of a SAW-less RF receiver front-end that includes a frequency translated notch filter (FTNF) are presented. An FTNF includes a passive mixer and a baseband impedance. The baseband impedance includes capacitors that form a low-Q band-stop filter. The passive mixer is configured to translate the baseband impedance to a higher frequency. The translated baseband impedance forms a high-Q notch filter and is presented at the input of the FTNF. The FTNF can be fully integrated in CMOS IC technology (or others, e.g., Bipolar, BiCMOS, and SiGe) and applied in wireless receiver systems including GSM, EDGE, Wideband Code Division Multiple Access (WCDMA), Bluetooth, and wireless LANs (e.g., IEEE 802.11). In addition, embodiments of an apparatus to protect SAW-less RF receiver front-ends are presented.

Abstract: To provide an antenna device adapted to interrupt jamming waves and enable cost reduction, a high-pass filter (HPF) adapted to interrupt general-use frequencies at least near a low-frequency side of a pass band intended for use is provided as a frequency selection circuit 11A on the antenna 1 side in an initial-stage LNA 2A. By setting a low-side cutoff frequency to 900 MHz, it is possible to prevent reception of frequencies in a general-use frequency band with a high frequency of use as jamming waves. That is, for example, it is possible to prevent reception of frequencies in 800 to 900 MHz band for mobile cellular telephones and higher harmonics thereof as jamming waves. Further, since an additional filter is not required in the antenna device, the circuit structure can be simplified.

Abstract: Methods and systems for a voltage-controlled oscillator (VCO) with a leaky wave antenna are disclosed and may include transmitting wireless signals via one or more leaky wave antennas in one or more tank circuits coupled to one or more VCOs. The VCOs may be two-point modulated. Two modulating signals may be communicated to the one or more VCOs via varactors coupled to tank circuits on the one or more VCOs. The varactors may include CMOS transistors with source and drain terminals shorted together. The one or more leaky wave antennas may be integrated on the chip, on a package to which the chip is affixed, or on a printed circuit board to which the chip is affixed. The VCOs may be integrated in a phase-locked loop and an output of the one or more VCOs in the phase-locked loop may be fed back via a multi-modulus detector.

Abstract: A receiving circuit is provided for performing reception of a plurality of band signals and suppression of blockers that remain in the plurality of band signals being received and converted in frequency. The receiving circuit includes a first low-pass filter that has a first pole position to suppress blockers remaining in a received signal by the first pole position, and a second low-pass filter that has a second pole position to suppress blockers remaining in a signal that has passed through said first low-pass filter by the second pole position. A switch that switches on/off an input-output path including the filters so that the received signal passes through said first filter without passing through the second filter when receiving a first band signal, while the received signal passes through both filters when receiving a second band signal different from the first band signal.

Abstract: Methods and systems for amplitude modulation using a leaky wave antenna are disclosed and may include amplitude modulating an output of one or more power amplifiers in a wireless device by modulating a bias current in the power amplifiers that are coupled to one or more leaky wave antennas. The leaky wave antennas may include a balun that may be integrated on the chip, on a package to which the chip may be affixed, and/or integrated on a printed circuit board to which the chip may be affixed. An output power of the power amplifiers may be adjusted by configuring a bias voltage on the leaky wave antennas. The bias voltage may be configured utilizing a DC to DC voltage controller. The bias current may be modulated via one or more switched current sources. The switched current sources may be binary weighted and/or may be current mirrors.

Abstract: A high-frequency receiver alleviates an influence of adjacent interference waves in a location where an identical set of broadcast channels can be received with different broadcast waves which are broadcast or relayed in frequency bands different from one another by satellites and ground repeater(s). The I and Q signals are passed to a pair of variable LPFs. A demodulation unit is provided for each of said different broadcast waves to demodulate the I and Q signals derived from the broadcast wave into a demodulated signal. One of the demodulated signals which has a better reception quality is selected for output. Based on a reception level and a noise evaluation information (e.g., the bit error rate) for a selected demodulated signal, a controller controls the bandwidths of the variable LPFs so as to optimize the reception level and the noise evaluation information for the selected demodulated signal.

Abstract: Systems for delivering a plurality of broadcast programs where the transmitter and receiver roll-off factors are mismatched. A system in accordance with the present invention comprises a transmitter comprising a modulator, and a plurality of receivers, each receiver in the plurality of receivers receiving the plurality of broadcast programs, each receiver in the plurality of receivers further comprising a demodulator; wherein the modulator has a first root-raised cosine filter having a first roll-off factor and each receiver has a second root-raised cosine filter having a second roll-off factor, the first roll-off factor being smaller than the second roll-off factor.

Abstract: An alternate adjacent channel interference (AACI) filter is integrated into an intermediate frequency (IF) channel select filter to filter received RF signals. The IF channel select filter is an IF staged structure comprising successive IF stages. Each of the successive IF stages is a 2-biquad integrator. The AACI filter is integrated into the first IF stage of the IF channel select filter by re-using circuit components such as an operational amplifier, an input resistor, and a shunt capacitor of the first IF stage. The shunt capacitor is coupled between a middle point of the input resistor and ground. The AACI filter is realized via different equivalent implementations of the re-used circuit components of the first IF stage. A value of the shunt capacitor of the AACI filter becomes a fixed-value when a value the input resistor is inversely proportional to the bandwidth of the AACI filter.

Abstract: A method of processing digital samples of a signal received at a receiver of a wireless communication system includes monitoring channel conditions and generating a channel indicator including at least one channel parameter by performing at least one of: estimating a channel mobility parameter and comparing it with a threshold; estimating a channel parameter of the energy of the channel outside a predefined temporal window and comparing it with a threshold; estimating a channel temporal duration parameter and establishing if it meets predetermined criteria; estimating a channel-zero location parameter and establishing if it meets predetermined criteria; estimating a received-signal signal-to-disturbance power ratio and comparing it to a threshold; estimating an estimated-channel-response signal-to-disturbance power ratio; estimating the degree of non-stationarity of the disturbance at the receiver input; and selecting one of a plurality of processing routines for processing the digital samples based on said c

Abstract: A signal processor for processing a receiving signal having a first usable frequency band and a second usable frequency band includes a first mixer for mixing the receiving signal with a first local oscillator signal, wherein a frequency of the first local oscillator signal is asymmetrical between the first usable frequency band and the second usable frequency band. The first mixer is implemented to obtain an in-phase signal and a quadrature signal, having a first signal portion representing a mixed image of the first usable frequency band, and having a second signal portion representing a mixed image of the second usable frequency band. The signal processor comprises a second mixer) for mixing the in-phase signal and the quadrature signal by using the second local oscillator signal.

Abstract: A method is disclosed for filtering communications channels in a telecommunications satellite to remove large unwanted interfering signals, which includes monitoring channels of an uplink signal by stepping across a channel with a first analog agile filter having a narrow bandwidth in relation to the channel, and at each step monitoring the signal within the channel step, in order to determine the presence of interfering signals, and configuring a second analog agile filter having an adjustable band stop function to block the interfering signals. The uplink signal has first and second signal paths for the uplink signal, and the method includes demultiplexing the channels of the uplink signal onto separate lines in the first path, carrying out the band stop function within the second signal path, and replacing with the remaining filtered part of the channel, by a switching operation, the demultiplexed version of the channel.

Abstract: In a filter circuit, resonators is connected in parallel between input and output terminal, an input signal is input through the input terminal and supplied to the resonators. Signal generators are connected to the resonators to control the resonators. The signal generators are controlled by a control unit so that the resonators are resonated to generate resonance signals at different resonant frequencies and at predetermined resonance phases. Thus, the output signal is set within a desired frequency range.

Abstract: A method for adjusting the volume and frequency response for the audio output in a mobile communication device comprises estimating the noise level of the environment surrounding the mobile communication device and then adjusting the volume and frequency response based on the estimated noise level.

Abstract: Method and apparatus to dynamically configure the signal reception selectivity of a plurality of transceivers is described. In one embodiment, a transceiver includes a receiver circuit having two or more filter circuits. Each of the filter circuits is configured to pass RF signals from a different portion of an overall receiver bandwidth. When two or more receivers in proximity to one another are simultaneously operating, the filter circuits of the respective receiver are dynamically configured to different RF frequency passbands to minimize interference and cross talk between receivers and transmitters.

Abstract: A receiving apparatus comprising: a frequency-fluctuation-detection unit to detect a frequency difference between a received and desired signals; a first-undesired-level-detection unit to output as a first-undesired level an amplitude-level-difference between the signals having passed through first-and-second-band-pass filters in the received signals; one or a plurality of second-undesired-level-detection units to output amplitude levels of signals having passed through third-and-fourth-band-pass filters in the received signals as second-and-third-undesired levels, respectively, and output a sum of the second-and-third-undesired levels as a fourth-undesired level; and a determination unit to determine whether an undesired state, where an adjacent-undesired signal is present, occurs according to the fourth-undesired level if an absolute value of the frequency difference is equal to or greater than a predetermined-reference value, and select any one of the first-to-third-undesired levels to be outputted accordi

Abstract: A waveform reconstruction circuit receives an rf signal from an antenna, digitizes it, and then generates an undistorted reconstructed waveform. The reconstructed waveform can then be conventionally mixed and demodulated to extract useful signal information with enhanced receiver fidelity and sensitivity.

Abstract: An integrated circuit radio receiver includes radio frequency (“RF”) front end circuitry for receiving and transmitting digital data received through a wireless interface. A baseband processor is operable to process the digital data received through the wireless interface. A plurality of digital filtering logic is included wherein each digital filtering logic includes a level of digital filtering based upon a received digital data signal format. The integrated circuit radio receiver includes logic that is operable to select between each digital filtering logic of the plurality of digital filtering logic based upon the received digital data signal format to process the digital data received through the wireless interface with the selected level of digital filtering.

Abstract: Embodiments of a frequency translated filter (FTF) are presented. An FTF includes a passive mixer and a baseband impedance. The baseband impedance includes a network of one or more passive components (e.g., resistors, inductors, and capacitors) that form a low-Q filter. The passive mixer is configured to translate the baseband impedance to a higher frequency. The translated baseband impedance forms a high-Q filter and is presented at the input of the FTF. The FTF can be fully integrated in CMOS IC technology (or others, e.g., Bipolar, BiCMOS, and SiGe) and applied in wireless receiver systems including GSM, Wideband Code Division Multiple Access (WCDMA), Bluetooth, and wireless LANs (e.g., IEEE 802.11).

Abstract: A communication device may include one or more circuits in an integrated transmitter and receiver that includes a transmit path and a receive path. The transmit path may include an I processing baseband transmit path and a Q processing baseband transmit path. The receive path may include an I processing baseband receive path and a Q processing baseband receive path. The one or more circuits may enable sharing a first common filter by the I processing baseband transmit path and the I processing baseband receive path. The one or more circuits may also enable sharing a second common filter by the Q processing baseband transmit path and the Q processing baseband receive path. The first common filter and the second common filter are independently programmable to adjust a phase and/or a gain of the said first common filter, and/or a phase and/or a gain of the second common filter.

Abstract: A radio receiver comprising: a frequency shifter for receiving a radio frequency signal including a wanted signal in a first frequency band and an interferer in a second frequency band overlapping the first frequency band, and for frequency shifting the radio frequency signal to form a frequency shifted signal, in which the first frequency band is shifted to a third frequency band below radio frequency and the second frequency band is shifted to a fourth frequency band; and a filter for receiving the frequency shifted signal and for attenuating the fourth frequency band relative to the parts of the third frequency band that do not include the fourth frequency band, wherein the filter is dynamically tuneable.

Abstract: Provided is a remote radio head receiver, including an antenna and an interference mitigation block. The antenna is configured to receive a signal. The interference mitigation block is configured to selectively pass and amplify the signal. The interference mitigation block does not include a liquefied gas cooling system.

Abstract: The present invention is a receiving circuit used for a cellular phone that is reduced in size and can realize low power consumption. In a signal reception circuit that is used in a cellular phone that perform transmission and reception of a plurality of band wireless signals and includes a low-pass filter for removing blockers unnecessary for signal reception, the low-pass filter 104 is composed of a plurality of filters composed of a plurality of different circuit configurations and having a plurality of different pole positions, switching between a filter for blocker removal and a filter configuration with reduced sensitivity degradation is performed by combining a plurality of filters for each signal reception band, and by performing power-off of an unnecessary filter portion in the filter configuration, power consumption is reduced.

Abstract: The present invention is an RF filter that translates impedances of an IF circuit to create a filter with an RF center frequency having the high Q roll-off characteristics of an IF filter. The RF filter is self-aligned with the frequency of an RF local oscillator. The RF filter has an impedance divider, which is formed by coupling an RF impedance circuit to a translated IF impedance circuit. The translated IF impedance circuit includes an RF passive mixer and an IF impedance circuit. The mixer translates the impedance of the IF impedance circuit by mixing an RF input signal with an RF local oscillator signal, which determines the RF center frequency. Filtered RF signals may be provided by the impedance divider. Filtered IF signals may be provided by the IF impedance circuit. To effectively translate and preserve the IF impedance characteristics, the IF impedance circuit presents a high impedance at harmonics of the RF local oscillator signal.

Abstract: An exemplary method is disclosed to accurately estimate the center frequency of a narrow-band interference (NBI). The exemplary method uses multi-stage autocorrelation-function (ACF) to estimate an NBI frequency. The exemplary method allows an accurate estimation of the center frequency of NBI in an Ultra-Wideband system. A narrow band interference (NBI) estimator based on such a method allows a low complexity hardware implementation. The exemplary method estimates the frequency in multiple stages. Each stage performs an ACF operation on the received signals. The first stage gives an initial estimation and the following stages refine the estimation. The results of all stages are combined to produce the final estimation. An apparatus based on such a multi-stage narrow band interference frequency detector is also disclosed to improve the accuracy by combining various filters with the detector.

Abstract: The invention discloses an interference cancellation circuit for a receiver to process an input signal which is carried on a first carrier frequency and includes a transmitted signal and at least one interference signals. The interference cancellation circuit comprises a down-converter for converting the input signal to dc location to generate a down-converted signal; a first path circuit for processing the down-converted signal to generate a first processed signal which includes the transmitted signal and the interference signals; a second path circuit for processing the down-converted signal to generate a second processed signal which includes only the interference signals; and a combiner for generating an output signal by combining the first processed signal and the second processed signal.

Abstract: Methods and systems for signal analysis in multiple radio carrier environments are provided. In one embodiment, a radio receiver comprises: an adaptive pass band filter that operates over a pass band of frequencies, the adaptive pass band filter subdividing the pass band into a plurality of sub-channels each comprising a narrower bandwidth than the pass band; and a signal analyzer receiving the plurality of sub-channels, the signal analyzer providing feedback to the adaptive pass band filter, wherein the adaptive pass band filter divides the pass band into the plurality of sub-channels based on the feedback; wherein the signal analyzer selectively generates an output comprising of at least one of the plurality of sub-channels.

Abstract: A communications system including: a plurality of sub-surface portable transceivers each including: a digital data source, a modulator coupled to the digital data source, a power amplifier coupled to the modulator and a loop antenna inductively coupled to the power amplifier; and a base transceiver including: an electrically insulated ferrite core antenna for receiving magnetic signals, an electric di-pole antenna for receiving ambient noise, a noise canceller coupled to the insulated ferrite core antenna and electric dipole antenna and responsive to the electric-dipole antenna to filter noise from signals received via the insulated ferrite core antenna, a demodulator coupled to the noise canceller and a decoder coupled to the demodulator.

Abstract: Provided is a wireless transceiving apparatus for variability of signal processing band, in which at least one resonator of an analog processor and a VCO are simultaneously controlled using a frequency synthesizer, and a frequency of the VCO and a resonance frequency of the analog processor are controlled to have a rational number ratio, thereby capable of varying the signal processing band. The wireless transceiving apparatus includes: an analog processor having a plurality of resonators on a path of transmission/reception signals, for performing analog signal processing; a digital processor for performing digital signal processing on an output signal of the analog processor or data to be transmitted to the analog processor; and a frequency synthesizer for providing a local oscillation (LO) frequency and a controlling signal to the resonators of the analog processor so as to vary a signal processing band of the analog processor.

Abstract: An adaptive wireless receiver and method thereof is disclosed in the present invention. The receiver includes an antenna, a bandpass filter, a front-end unit and a demodulator. Elements inside the front-end unit can be reused when the receiver operates in a zero intermediate frequency (ZIF) mode and in a low intermediate frequency (LIF) mode. The front-end unit includes a first and second down-conversion mixer, an analog filter, a first and second analog-to-digital converter (ADC), and a digital filter.

Abstract: An aspect of the present invention is drawn to a receiver operable to receive a first signal transmitted on a first carrier and to receive a second signal transmitted on a second carrier. The receiver includes a first filter, a second filter and a nonlinear compensator. The first filter is arranged to receive the first signal and to generate a first filtered signal. The second filter is arranged to receive the second signal and to generate a second filtered signal. The nonlinear compensator is arranged to output a first compensating signal based on the first filtered signal and the second filtered signal and to output a second compensating signal based on the first filtered signal and the second filtered signal. Further, the nonlinear compensator can reduce one of nonlinear interference within the first filtered signal and nonlinear interference between the first filtered signal and the second filtered signal.

Abstract: Techniques are described that can be used to reduce noise attributable to jitter in a received signal. Multiple filters may be available. The number of available filters may correlate to a period of channel-related jitter in terms of clock cycles. One of the filters may be activated for a particular clock cycle. The activated filter may provide a noise reducing signal based on a reference signal and error identified in a received signal. A filter may be used to provide a signal to reduce noise attributable to error signals from interleaved jittered channels.

Abstract: To provide an antenna device adapted to interrupt jamming waves and enable cost reduction, a high-pass filter (HPF) adapted to interrupt general-use frequencies at least near a low-frequency side of a pass band intended for use is provided as a frequency selection circuit 11A on the antenna 1 side in an initial-stage LNA 2A. By setting a low-side cutoff frequency to 900 MHz, it is possible to prevent reception of frequencies in a general-use frequency band with a high frequency of use as jamming waves. That is, for example, it is possible to prevent reception of frequencies in 800 to 900 MHz band for mobile cellular telephones and higher harmonics thereof as jamming waves. Further, since an additional filter is not required in the antenna device, the circuit structure can be simplified.

Abstract: A wideband signal comprising both a wanted signal and narrowband interference is received in a wideband receiver. The receiver comprises an interference detection unit comprising a set of sub-band filters. With the aid of the sub-band filters the received signal is processed to detect a sub-band containing the narrowband interference in time domain.

Abstract: A radio receiver front-end includes first and second RF receiver sections and an RF combining module. The first RF receiver section is coupled to receive an inbound RF signal and provide to a first representation of the inbound RF signal, wherein the inbound RF signal includes a desired signal component and an undesired signal component. The second RF receiver section is coupled to receive the inbound RF signal and to provide a second representation of the inbound RF signal. The RF combining module is coupled to combine the first and second representations of the inbound RF signal to produce a desired RF signal, wherein the desired RF signal includes the desired signal component and an attenuated representation of the undesired signal component.

Abstract: The high-frequency IC according to an embodiment of the invention includes a mixer down-converting the RF signal into an IF signal with a given center frequency lower than that of the RF signal, a first-order low-pass filter with a pass band set narrower than a bandwidth of the IF signal down-converted by the mixer, and an active low-pass filter removing a signal outside the bandwidth of the IF signal.

Abstract: An integrated front-end filter for a tuner provides an array of from several to a multitude of passbands, each for passing at least one but less than all channels designated in a band of frequencies. Each passband is exclusively selectable. The integrated front end filter includes at least one active filter unit with an active reactance element in either of fixed and variable filter configurations and a decoder coupled to said at least one active filter unit and being responsive to a control signal for selecting a one of the passbands. In one example a multitude of active filter units of fixed filter configuration provide the multitude of passbands. Each data is stored at a predetermined location and reproduced in response to a corresponding control data signal from a tuner controller. Each data characterizes one of the plurality of passbands. The filter element is switchable from one passband to another in response to the control data signal.

Abstract: An embodiment pertains to a phase locked loop (PLL) circuit. The PLL includes a voltage controlled oscillator which outputs a signal at a desired frequency. A phase detector is coupled to an output from the voltage controlled oscillator. The phase detector compares the phase of a signal output from the voltage controlled oscillator (VCO) with the phase of a reference signal. A loop filter is coupled to the VCO and the phase detector. The loop filter has a locking mode of operation for locking the phase of the VCO signal to the phase of the reference signal. The loop filter can subsequently be placed in a tracking mode of operation which adjusts the phase of the VCO signal to track the phase of the reference signal.

Abstract: A filtering apparatus and method using a reference feedback circuit is disclosed. The filtering apparatus includes an input signal generating unit, a reference feedback unit, and a band-pass filter. The input signal generating unit generates an input signal in an allocated band that the receiver uses. The reference feedback unit compares the power of the input signal with that of an output signal and generates a reference signal. The output signal is generated as a band-pass filter filters the input signal with respect to the allocated band. The band-pass filter adjusts the quality factor (Q factor) of a receiver according to the reference signal and passes frequencies of the input signal input to the receiver only within the allocated band.

Abstract: An interference-robust receiver includes an RF signal processor, a frequency conversion interface and an analog signal processor. The RF signal processor provides an RF signal. The frequency conversion interface includes a passive mixer for generating an intermediate frequency signal by down-converting an in-band part of the RF signal to a passband of a filter and down-converting an out-of-band part of the RF signal to a stopband of the filter. The filter can thus filter the intermediate frequency signal with the passband and the stopband.

Abstract: Techniques for filtering noisy estimates to reduce estimation errors are described. A sequence of input values (e.g., for an initial channel impulse response estimate (CIRE)) is filtered with an infinite impulse response (IIR) filter having at least one coefficient to obtain a sequence of output values (e.g., for a filtered CIRE). The coefficient(s) are updated based on the sequence of input values with an adaptive filter, a bank of prediction filters, or a normalized variation technique. To update the coefficient(s) with the adaptive filter, a sequence of predicted values is derived based on the sequence of input values. Prediction errors between the sequence of predicted values and the sequence of input values are determined and filtered to obtain filtered prediction errors. The coefficient(s) of the IIR filter are then updated based on the prediction errors and the filtered prediction errors.

Abstract: Systems and methods for interference cancellation in which a first signal having a first frequency may be cancelled with a second frequency having a second and different (e.g., lower) frequency by employing sampling to cancel the first signal with the separate signal at the sample instances.

Abstract: Provided are a method, system, and device directed to a receive path for a node in a communication system such as a Radio Frequency Identification (RFID) system. In one aspect, the receive path includes a filter operable in multiple modes and configurable to have different bandwidths in the various modes of operation. For example, in one mode, the filter samples a DC component while configured to have a relatively wide bandwidth. As another example, the filter may be operated in another mode to hold the sampled DC component while the filter is configured to have a zero or close to zero bandwidth. As yet another example, the filter may be operated in still another mode to filter received signals and cancel the sampled DC offset from the received signals while configured to have a relatively narrow bandwidth. Additional embodiments are described and claimed.

Abstract: A full-duplex RF communication system and corresponding methods use digital adaptive filters for interference cancellation. As provided, the techniques allow full-duplex radio frequency communication without frequency-, time-, or code-division multiplexing and without the use of hardware RF cancellers. Such techniques may be useful for wireless communication, such as cellular communication, radio communication, broadcasting, short-range point-to-point communication, wireless sensor networks, and wireless computer networks.

Abstract: A quadratic amplitude matching system and associated method with an associated tuning control system is provided for continuously and automatically tuning a quadratic amplitude matching filter (QAMF) to a band center of an interfering signal to provide improved rejection of an interfering signal coupled from a transmission antenna into a local receive antenna in the presence of local multi-path, thereby providing improved interference cancellation system performance. The matching control system is provided as an element of an interference cancellation system.

Abstract: A system and method in a radio receiver for joint synchronization and noise covariance estimation of a received signal. A spatially and temporally stacked signal model, whereby successive samples of temporally adjacent received signal vectors and corresponding training vectors are stacked, is used in the derivation of the estimation problem. The Toeplitz structure of the channel response matrix is neglected in the formulation of the estimation problem. The resulting estimator jointly estimates a synchronization position, a channel response matrix, and a noise covariance matrix. An estimate of a whitened channel is then computed based on the noise covariance matrix and the estimate of the channel response matrix.

Abstract: In an apparatus, method, and system for reducing interference with an input signal to an FM receiver, a plurality of inputs are filtered by a first stage of filters. The outputs are received by an interference detector and further processed by a second filtering stage, an energy calculation stage, and a comparator stage. A switch, responsive to the outputs of the comparator stage, may output one of the first stage filter outputs based on a first set of comparator outputs and may output an interpolated value determined by the first stage filter outputs and based on a second set of comparator outputs.

Abstract: An apparatus and method are provided for minimizing noise on a power supply line (105) of a mobile radio, such as generated in a vehicular environment. An adaptive power supply conditioner (100) detects unwanted noise on the vehicle's power supply line (105) and via the use of an adaptive noise canceller (140), generates a cancellation signal (145) having the same amplitude but opposite phase of the input signal's detected noise. The cancellation signal (145) is fed forward and combined with the power supply line (105) in order to minimize unwanted noise on the supply line (105) leading to the mobile radio. The conditioner's output (165) is checked for further error and is fed back to the adaptive noise filter (140) for further filtering and the generation of an updated cancellation signal based on current noise conditions.

Abstract: A radio frequency (RF) tuner includes a programmable tracking filter bank receiving an RF input and outputting a filtered RF signal. A mixer stage receives the filtered RF signal and outputs a first quadrature component of the filtered RF signal and a second quadrature component of the filtered RF signal. Two variable gain amplifiers receive the first and second quadrature components and output amplitude-controlled I and Q components of the filtered RF signal. In one embodiment, the programmable tracking filter bank includes a plurality of tank circuits each connected to the RF input through an impedance. Each tank circuit include an inductor and a capacitor connected in parallel thereby forming an LC network, and a plurality of switched capacitors in parallel with the LC network and switched in and out of the tank circuit by programmable switches. In another embodiment, the programmable tracking filter bank includes a plurality of peaked low-pass circuits each connected to the RF input through an impedance.

Abstract: A notch filter suitable for attenuating certain frequencies of a radio-frequency signal includes an input for receiving the radio-frequency signal and an output for the output of a portion of the radio-frequency signal, first and second capacitive means, at least one inductor and a negative resistance circuit suitable for compensating the resistive losses of said at least one inductor. The inductor and the first and second capacitive means are placed to produce a resonator and the filter comprises a control device suitable for controlling the negative resistance circuit. The input impedance of the filter comprises a pole and a zero, with the pole depending on the second capacitive means and the zero depending on both the first and second capacitive means. The first and second capacitive means are variable and the control device is suitable for controlling the first and second capacitive means.

Abstract: An apparatus and method for local oscillator calibration compensates for filter passband variation in a mixer circuit, such as a receiver circuit. The receiver includes at least a mixer circuit and a filter coupled to the output of the mixer. During operation, the mixer mixes an RF input signal with a first local oscillator (LO) signal to frequency translate a selected channel in the RF input signal into the passband of the filter. During a calibration mode, the RF input signal is disabled, and the first LO signal is injected into the filter input by leaking the first LO signal through the mixer circuit. The frequency of the LO signal is then swept over a frequency bandwidth that is sufficiently wide so that the actual passband is detected by measuring the signal amplitude at the output of the bandpass filter, thereby determining any variation in the passband of the filter from the expected passband.