Abstract: Techniques are disclosed for eliminating or otherwise sufficiently suppressing spurious signals. The techniques are particularly useful in applications such as those that employ aggressor frequency sources along with a frequency conversion or mixing function, and especially applications implemented as a system-on-chip. In the spur-training mode, a spur-canceller circuit identifies spurious tones associated with the host system to neutralize those tones when running in a normal mode. The tones are neutralized using a comb generator with variable phase and gain by way of cancellation with comb output signals having substantially the same amplitude and a phase that is 180° out of phase with the aggressor tone to be cancelled.

Abstract: A mixer for downconversion of RF signals includes at least one RF transistor (305); at least one switching pair (303) connected to the drain current (301) of the at least one RF transistor (305); and a common mode sensing component (300) configured to detect deviations in the common mode output of the switching pair (303) from a specified output; wherein the deviations modify the current of the at least one switching pair (303).

Abstract: A technique to remove second order and third order nonlinearity distortions caused by a blocker signal at an input of a radio receiver. An envelope detector is utilized at an input of the RF front-end of the receiver to obtain a magnitude of the overall signal. The output of the envelope detector is then processed at baseband to estimate coefficients that relate to the distortion. Once the coefficients are obtained, the coefficients are applied at an I/Q imbalance correction stage to also correct for the distortion by cancelling the distortion from the received signal.

Abstract: Circuits and methods are disclosed for compensating for received signal distortion caused by non-linearities in wideband receivers. An exemplary receiver includes a distortion waveform generator configured to approximate non-linear response characteristics of a downconverter circuit used to downconvert the received radio frequency signal. The resulting estimated distortion waveform is filtered, using filter(s) substantially similar to those used for filtering an intermediate frequency signal that includes the desired signal and non-linear distortion products caused by strong interfering signals. The filtered estimated distortion waveform and intermediate frequency signal are sampled, to obtain a sampled distortion signal and a sampled signal of interest. The sampled distortion signal and the sampled signal of interest are divided into a plurality of frequency channels.

Abstract: A method is provided for processing a signal containing regular or quasi-regular elements of unwanted signal. The method establishes timing characteristics of the unwanted signal elements in a portion of the signal. A time domain window function is generated using the established timing characteristics. The generated window function is applied to the signal portion to selectively reduce the amplitude of the unwanted signal elements relative to the amplitude of other elements of the signal.

Abstract: A method of signal distortion correction in a telecommunications channel, the method comprising modeling predicted signal distortion of an electromagnetic (EM) signal using one or more non-linearity model parameters of a signal distortion model, calculating and transferring one or more coefficients of the one or more non-linearity model parameters to a signal transmit location, pre-distorting the signal using an inverse function based on the one or more non-linearity model parameters, and transmitting the pre-distorted signal over the telecommunications channel containing a non-linear amplifier to a remote receiving device.

Abstract: Methods and systems for optimal frequency planning for an integrated communication system with multiple receivers may include adjusting a center frequency of a low IF signal to reduce interference by a second order interference signal. The center frequency may be adjusted to avoid high power portions of the second order interference signal. The interference level corresponding to a center frequency may be determined by, for example, a SNR of the low IF signal, or by determining a BER for the low IF signal. The center frequency of the low IF signal may be dynamically adjusted to keep second order interference level at an acceptable level. Adjusting the center frequency of the low IF signal may also comprise keeping the low IF signal from being blocked by a DC component of the second order interference signal.

Abstract: Sampling may be employed to cancel an analog input radio frequency (RF) signal by using an upconverted analog cancellation RF signal to cancel the analog input RF signal at the sample instances. At least two sampling paths may be employed, a signal path and a cancel path, and direct RF bandpass sampling may be included in both the signal and cancel paths.

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: An apparatus and method for signal optimization is disclosed. This disclosure relates to improved device and method for improving performance and reducing cosite interference for an antenna array. More particularly, this description relates to a device and method for equalizing signals for communication receivers, and more particularly, to a device and method for matrixed adaptive equalizing configured to a plurality of antennas for receiving one or more signals each designated for one of a plurality of receivers.

Abstract: A high linearity mixer circuit includes a commutation network comprising four switches to provide an electrical coupling between a first pair of circuit nodes and a second pair of circuit nodes, whereas the coupling has two states and is controlled by a pair of complementary logical signals. The mixer circuit further comprises a first pair of current-sourcing devices coupled to the first pair of circuit nodes and a second pair of current-sourcing devices coupled to the second pair of circuit nodes. The mixer circuit further includes a pair of capacitors to provide AC coupling, either between the first pair of circuit nodes and a first external circuit, or between the second pair of circuit nodes and a second external circuit.

Abstract: A communication system includes a first transmission channel with a first end and a second end. The first and second ends are coupled to first and second transformers. First and second end transceivers transmit and receive signals via the first and second transformers. A first signal is supplied at the first end and comprises a transmission signal component of the first transceiver and a receive signal component from the second transceiver. The communication system comprises a replica transmitter that generates a replica of the transmission signal component of the first transceiver. A filter filters the replica signal. An active resistive summer receives the first signal and the filtered replica signal as inputs to reduce the transmission signal component at an output of the active resistive summer. The active resistive summer includes a feedback element.

Abstract: A highly linear mixer and method for cancelling field effect transistor channel resistance modulation are provided. At least a portion of the voltage of an input signal is added to a drive signal to cancel distortion arising from modulation of the voltage of the input signal.

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: A system includes a transceiver configured to receive a composite signal. The composite signal is a composite of a transmit signal and a receive signal. A replica transmitter is configured to generate a replica transmit signal based on the transmit signal. A transmit canceller is configured to recover the receive signal at least in part by resistively summing the composite signal and the replica transmit signal.

Abstract: A system for correcting a second order intermodulation product in a direct conversion receiver is provided. The system includes a cross-covariance system receiving a data signal and a second order intermodulation estimate signal and generating a cross-covariance value. An auto-covariance system receives the second order intermodulation estimate signal and generates an auto covariance value. A buffer system stores a second order intermodulation product correction factor. A divider receives the cross-covariance value, the auto-covariance value and the second order intermodulation product correction factor and generates a running average second order intermodulation product correction factor.

Abstract: A wireless communication device which permits reduction in the scale of circuitry as well as in the power consumption. The wireless communication device includes an array of antennas, an adaptive array searcher, and a data demodulator. The adaptive array searcher detects the phase difference between the antennas and estimates the direction of arrival of received radio waves. The data demodulator demodulates the radio signal received by the antennas. The adaptive array searcher shares part of circuitry with a calibrator which performs calibration by correcting the phase difference caused between antenna channels in the wireless communication device, and thus has a calibration function incorporated therein.

Abstract: A wireless communication unit includes a transmitter for processing a baseband transmit signal to produce a first radio frequency signal. A receiver is arranged to convert a second radio frequency signal to a baseband receive signal, where the receiver has a summation module arranged to add a cancellation signal to the baseband receive signal. A selectivity element is arranged to couple the transmitter and the receiver to an antenna, where a reduced portion of the first radio frequency signal is introduced into the second radio frequency signal thereby creating a second order inter-modulation distortion component in the baseband receive signal. An adaptive estimator module has a filter for filtering the baseband receive signal to remove dc offsets associated with the second order inter-modulation distortion component and generate the cancellation signal based on the baseband transmit signal and the filtered baseband receive signal for inputting to the summation module.

Abstract: A circuit is provided for suppression of second-order intermodulation in a double-balanced mixer circuit. The circuit includes a duplicate transconductor element for duplicating AC current in a transconductor pair of the double-balanced mixer circuit. A fundamental cancellation element cancels a fundamental component of an AC current of the duplicate transconductor element, while preserving a second-order intermodulation component. A phase inversion element feeds an output current of the fundamental cancellation element to the transconductor pair of the double-balanced mixer circuit, to substantially remove the second-order intermodulation component from a differential output of the double-balanced mixer circuit.

Abstract: An apparatus, a method and a system for correcting a phase imbalance are described. Embodiments may measure the phase imbalance inherent in a tuner and use the imbalance measure to correct the output of the tuner. Embodiments may include a tone generator to produce a single frequency tone and a tuner to receive the single frequency tone and output an intermediate frequency. The intermediate frequency may be corrected by a correction loop. Other embodiments are described and claimed.

Abstract: A cross polarization interference canceling apparatus of the present invention includes: error detector 26 for extracting a difference between a demodulated signal that is the main polarization signal in which compensation for cross polarization interference has been made and the received signal which indicates an ideal state of the main polarization, and outputting an error signal that indicates the extracted difference; phase noise detector 27 for outputting a phase noise difference by comparing a cross polarization interference compensating signal that is the opposite polarization signal in which compensation for cross polarization interference has been made with the error signal; a control signal generator for generating a control signal corresponding to the phase noise difference; and phase rotator 18? disposed prior to, or posterior to, a cross polarization interference canceller for generating the cross polarization interference compensating signal, for controlling the phase of the cross polarization i

Abstract: A Radio Frequency (RF) receiver includes a low noise amplifier (LNA) and a mixer coupled to the output of the LNA. The gain of the LNA is adjusted to maximize signal-to-noise ratio of the mixer and to force the mixer to operate well within its linear region when an intermodulation interference component is present. The RF receiver includes a first received signal strength indicator (RSSI_A) coupled to the output of the mixer that measures the strength of the wideband signal at that point. A second received signal strength indicator (RSSI_B) couples after the BPF and measures the strength of the narrowband signal. The LNA gain is set based upon these signal strengths. By altering the gain of the LNA by one step and measuring the difference between a prior RSSI_B reading and a subsequent RSSI_B? reading will indicate whether intermodulation interference is present.

Abstract: Third-order intermodulation products (IM3) are attenuated in RF receivers by providing a typical main signal path and a parallel auxiliary signal path in which the IM3 products are accentuated, and the output from the main signal path is adaptively filtered to attenuate the IM3 products. In one embodiment, a multirate filter bank (MRFB) with asymmetric analysis and synthesis sections is used to detect and isolate the IM3 products. In another embodiment an analog nonlinear term generator is placed at the front of the auxiliary signal path. The analog nonlinear term generator takes advantage of the nonlinearities of a differential MOSFET circuit and a multiplier to extract the IM3 products in the RF input signal. The outputs of the main signal path and the auxiliary signal path are inputs to a complex least mean squares filter to attenuate the IM3 products in the resulting signal.

Abstract: A method for successive interference cancellation in code division multiple access (CDMA) systems is provided that uses variable interferer weights. This method allows interfering signals to be cancelled in order to recover a transmitted data signal. This method involves receiving the data signal subject to interference from at least one interfering signal. A first interfering signal is identified. Then an interferer weight coefficient associated with the first interfering signal is generated. This allows the first interfering signal to be cancelled from the received data signal using the interferer weight coefficient. These processes may then be reiterated for other interfering signals. It is then possible to recover the transmitted data signal from the received data signal.

Abstract: A system and method are provided for calibrating Amplitude Modulation to Phase Modulation (AM/PM) pre-distortion in a transmitter operating according to a polar modulation scheme. In general, phase modulation is disabled during transmission of an actual polar modulation signal. As a result, the transmitter provides a radio frequency (RF) output signal having an amplitude modulation component and ideally a constant phase. However, the AM/PM distortion of the transmitter creates a phase modulation component in the RF output signal. The phase component of the RF output signal, which is the AM/PM distortion of the transmitter, is measured by test equipment. The AM/PM pre-distortion applied by the transmitter is then calibrated based on the measured AM/PM distortion such that the AM/PM distortion of the transmitter is substantially reduced.

Abstract: Aspects of a method and system for I/Q branch equalization in OFDM systems may include determining a transfer function mismatch between an in-phase processing branch, and/or a quadrature processing branch in an OFDM receiver. The determined transfer function mismatch may be compensated for, by applying equalization after a fast Fourier transform (FFT) in an in-phase processing branch and/or a quadrature processing branch. The OFDM system may be compliant with, for example, UMTS LTE (EUTRA), WiMAX (IEEE 802.16), DVB-H, and WLAN (IEEE 802.11). A transfer function may be measured for an in-phase branch filter and/or quadrature branch filter to determine the transfer function mismatch. The transfer function mismatch may be compensated for, in frequency domain by the equalizer. The transfer function mismatch may comprise magnitude and/or phase response mismatch, wherein the magnitude and/or phase response mismatch may be a function of frequency.

Abstract: An amplifier comprises a source degeneration inductance and at least two field effect transistors coupled in parallel and having mutually different gate biasing. Source connections of the field effect transistors are coupled along different positions of the source degeneration inductance.

Abstract: An RF receiver and an RF receiving method are provided using a baseband signal in which a DC offset is removed. In the RF receiver, a noise phase removing unit generates a phase controlled local signal PLOQ in which a phase of a Q signal of a local signal LOQ is controlled, by synthesizing a received RF signal RXIN and the Q signal of the local signal LOQ. A down converter generates a signal in which a DC offset from noise introduced into the received RF signal RXIN is removed, when synthesizing the received RF signal RXIN and the phase controlled local signal PLOQ for frequency-down conversion.

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: A noise level of an input signal is determined by a noise calculation module. based on the noise level, a boundary setting module sets a reduced constellation boundary interval. This reduced constellation boundary interval is employed by an equalizer to perform adaptive equalization of the input signal.

Abstract: A wireless communications terminal prevents radio interferences caused by other wireless communications concurrent with a contactless communication. A wireless communications terminal receives, in a contactless communication, a command from a reader/writer via a second wireless communications section, and analyzes the received command. The wireless communications terminal controls a wireless communications control section to deactivate or temporarily deactivate the function of a first wireless communications section depending on the analysis of the command. After the function of the first wireless communications section is deactivated or temporarily deactivated, the wireless communications terminal accesses a memory area of an IC card microcomputer system as specified by the command to perform a contactless communication.

Abstract: Provided is an apparatus and method for canceling interference by a base station in a wireless mobile communication system. The method includes measuring a state of a channel with a mobile station, determining metric function values for channels that act as interference to the channel of the mobile station, selecting a predetermined number of interference channels in descending order of the metric function values, determining a weight vector for removing a signal transmitted over the interference channels, and applying the determined weight vector to a transmission signal and transmitting the weight vector applied signal.

Abstract: A receiver and a method are applied in a wireless communication system for detecting interference with a coexisting radar system. A signal received from an antenna is fed through an analog part and a subsequent digital part of said receiver. The receiver has an element with a-priori known attenuation values for a predefined set of frequencies, a first branch-off element for deriving a first detection signal from the signal before the element and a second branch-off element for deriving a second detection signal from the signal after the element. The receiver processes the first and the second detection signal such that a difference between the first and second detection signal is comparable with a threshold value, where the threshold value depends on the a-priori known attenuation values of the element. Depending on the comparison result, a frequency is identified as interfering or not a co-existing radar system.

Abstract: A method for determining at least one operational transmit power Snk over a communication channel (Ln) coupled to a disturbance causing transceiver (n) for at least one tone (k), comprises the steps of provision of at least one reference victim communication channel (Lref) for representing at least one reference victim for all victim communication channels which are degraded by cross-talk interferences by said communication channel (Ln), and maximizing the data rate (Rref) over said at least one reference victim communication channel (Lref) under the constraint that the data rate over said communication channel (Ln) achieves a target rate (Rntarget) without exceeding a power constraint (Pnmax).

Abstract: Systems for suppressing image noise are provided. In this regard, one embodiment includes a system for suppressing image noise comprising a low noise amplifier (LNA) configured to amplify a received RF signal, an RF variable gain attenuator with an image rejection filter with programmable bandwidth configured to suppress image noise and image interference, and an RF mixer configured to perform frequency translation.

Abstract: A mobile terminal capable of breaking a phase-noise signal caused by a high power transmission signal of a mobile phone such as GSM when receiving digital TV broadcasting such as DVB-H and a method of reducing interfering phase-noise in the mobile terminal. The mobile terminal includes a first RF transmitter/receiver; a first signal coupler; a phase-noise filter; a phase shifter; a VGA amplifier; and a signal combiner.

Abstract: A Multi-mode-multi-band direct conversion receiver with complex I and Q channel interference mitigation processing for cancellation of intermodulation products (IMPs) are described. In one embodiment, a method comprising over sampling of the entire receiver passband to acquire the IMP source signals that can generate IMPs within the signal of interest (SOI), generate a coherent complex I-Q channel estimates of the interference, generating estimates of 2nd and 3rd order IMP products, sampling of the transmitter feed thru signal and blocking signals and computing the cross modulation products estimate, using the cross modulation cancellation to cancel of the effects of the on chip transmitter feed thru to support building a single transceiver chip with full duplex operation, and creation of an estimate of the DC offset in the receiver in a closed loop fashion to cancel the DC offset in the I and Q channels independently and simultaneously, and adjusting the rate of update to match system parameters.

Abstract: A communication circuit includes a replica circuit that generates first and second single-ended replica transmit signals. When one of the first and second single-ended replica transmit signals is asserted, the other of the first and second single-ended replica transmit signals is not asserted. A converter circuit includes a differential amplifier including first and second inputs that receive the first and second single-ended replica transmit signals, respectively. The converter circuit converts the first and second single-ended replica transmit signals to a differential replica transmit signal. A receive circuit generates a differential receive signal based on a differential composite signal and the differential replica transmit signal.

Abstract: Techniques to perform adaptive interference cancellation are described. A first apparatus may include a timing recovery module to produce a timing recovery command signal, an interference canceller to receive an interference reference signal and produce an interference canceller signal, and an interpolator to couple to the timing recovery module and the interference canceller, the interpolator to receive the timing recovery command signal and the interference canceller signal and produce an interpolated interference canceller signal. A second apparatus may include a time-domain interference canceller to receive an interference reference signal and produce a time-domain interference canceller signal and a frequency-domain interference canceller to receive the interference reference signal and produce a frequency-domain interference canceller signal. Other embodiments are described and claimed.

Abstract: An integrated automatic IIP2 calibration architecture for wireless transceivers is disclosed. The architecture enables a wireless transceiver to generate a test radio frequency (RF) signal having a second order tone with minimal additional circuitry. In particular, the test RF signal is generated using a combination of native transceiver circuits and test adaptor circuits. Native transceiver circuits are those circuits implemented on the transceiver chip for executing native transceiver functions during normal operation, which can be used for generating the test (RF) signal. Test adaptor circuits are added to the transceiver chip, more specifically to the native circuits, for enabling the native circuits to generate the test RF signal in a self-test mode of operation. Circuits for implementing a particular IIP2 minimizing scheme can be included on the transceiver chip for automatic IIP2 calibration during the self-test mode of operation.

Abstract: This disclosure relates to linearization in polar modulators of wireless communication devices, to attain linear amplification and high power efficiency during transmission.

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: A zero-IF receiver includes an adaptive filter that is enabled when intermodulation distortion is detected. The adaptive filter is configured as a notch filter that is centered at the location of the second-order intermodulation distortion, which, in a zero-IF receiver, is at zero Hertz. In a preferred embodiment, the frequency response of the high pass filter that is typically used in a conventional zero-IF receiver is adjusted when intermodulation distortion is detected. Preferably, the detection of the intermodulation distortion is based on one or more of the digital baseband signals, for ease of implementation, but analog processing may also be employed.

Abstract: Systems and methods that are adapted to avoid radio frequency interference, electromagnetic interference, and/or electromechanical interference originating from modules, peripherals and interconnects of an electronic device, such as a mobile terminal, that are generating unintentional radiation (e.g. memory cards, camera flashes, data buses etc.) and coupling to the radios of the same electronic device are disclosed. The systems may include a controller unit that schedules the operation of the components to avoid concurrent operation of radios and sensitive peripheral devices which may interfere with each other during concurrent operation.

Abstract: The present invention relates to a method for the transmission of data in a multi-carrier system, provided with a frequency band, the carrier frequencies of which are distributed in a sub-carrier band, dividing the frequency band. On the transmission side, dependent on current transmission properties, an adaptive pre-emphasis of the transmission signal is carried out for a part of the carrier frequencies in the sub-carrier band. The transmitter thus has the capacity to determine current transmission properties as well as adaptive pre-emphasis of a part of the carrier frequencies in the sub-carrier band of the transmission signal.

Abstract: The present invention is related to a partially overlapped single-carrier crosstalk signal cancellation method and an apparatus using the same. For this purpose, the present invention provides a crosstalk canceller including a pre-processor for frequency down-shifting an input signal, a crosstalk signal cancellation module for canceling the crosstalk signal by dividing the input signal by an interpolation ratio, a post-processor for converting an output of the crosstalk signal cancellation modulation into a passband signal, and an error feedback processor for performing a decimation operation on a residual crosstalk signal and feeding backing the decimated residual crosstalk signal to the crosstalk signal cancellation module.

Abstract: Systems and methods are described for carrier phase synchronization for improved AM and TV broadcast reception. A method includes synchronizing the phase of a carrier frequency of a broadcast signal with the phase of a remote reference frequency. An apparatus includes a receiver to detect the phase of a reference signal; a phase comparator coupled to the reference signal-phase receiver; a voltage controlled oscillator coupled to the phase comparator; and a phase-controlled radio frequency output coupled to the voltage controlled oscillator.

Abstract: An integrated circuit containing a communication channel is described. This communication channel includes: a transmit circuit configured to transmit signals; a link coupled to an output of the transmit circuit; a receive circuit coupled to the link; and a clamping circuit coupled to the link. Note that the transmit circuit is capacitively coupled to the receive circuit via the link. Furthermore, the clamping circuit is configured to compensate for leakage current on the link by maintaining a voltage on the link corresponding to a logical “1” or a logical “0.” This voltage is based on a history of the transmitted signals.

Abstract: An electrical circuit in a communications channel includes a first sub-circuit having a first input which receives a composite signal that includes a transmission signal component and a receive signal component, a second input which receives a replica transmission signal, a third input which receives an analog baseline correction current, and an output which provides a receive signal which comprises the composite signal minus the replica signal. A second sub-circuit for controls the analog baseline correction current, so that the magnitude of the composite signal does not exceed a predetermined value of an operating parameter of the electrical circuit. The composite signal, the replica transmission signal, and the analog baseline correction current are directly connected together at a common node of the first sub-circuit.

Abstract: A derivative superposition circuit for linearization includes a first active element that is provided with first to third terminals and in which the magnitude and direction of current flowing from the second terminal to the third terminal changes on the basis of the magnitude of a voltage applied between the first and second terminals; and a second active element that is provided with first to third terminals and has complementary characteristics with the first active element. The first terminals of the first and second active elements are connected to each other so that a predetermined operational bias voltage is maintained by first and second power supplies through a first impedance, and are connected to an input end through a second impedance. The third terminals of the first and second active elements are connected to an output end, and the second terminals of the first and second active elements are connected to the second power supply through a third impedance.