Abstract: A modulation circuit for use in a radiofrequency transmitter includes a local oscillator circuit configured to generate one or more local oscillator signals at a desired frequency and with a duty cycle at or about twenty-five percent, and a modulator configured to generate one or more modulated signals responsive to the one or more local oscillator signals and one or more baseband information signals. In at least one embodiment, the modulation circuit includes a modulator comprising a combined mixing and transconductance circuit that includes a transistor circuit for each baseband information signal serving as a modulation input to the modulator. Each transistor circuit comprises a first transistor driven by the baseband information signal and coupling a modulator output node to a corresponding transconductance element, and a second transistor driven by one of the one or more local oscillator signals and coupling the corresponding transconductance element to a signal ground node.

Abstract: A modulation circuit for use in a radiofrequency transmitter includes a local oscillator circuit configured to generate one or more local oscillator signals at a desired frequency and with a duty cycle at or about twenty-five percent, and a modulator configured to generate one or more modulated signals responsive to the one or more local oscillator signals and one or more baseband information signals. In at least one embodiment, the modulation circuit includes a modulator comprising a combined mixing and transconductance circuit that includes a transistor circuit for each baseband information signal serving as a modulation input to the modulator. Each transistor circuit comprises a first transistor driven by the baseband information signal and coupling a modulator output node to a corresponding transconductance element, and a second transistor driven by one of the one or more local oscillator signals and coupling the corresponding transconductance element to a signal ground node.

Abstract: Adaptation is introduced into allocation of uplink and downlink subframes in wireless communication systems that support full-duplex and half-duplex mobile terminals, thus reducing interference between mobile terminals. In an exemplary method for allocating uplink and downlink timeslots in a wireless communication system supporting full-duplex and half-duplex mobile terminals, a base station determines that a mobile terminal is capable of only half-duplex operation and allocates one or more uplink subframes and one or more downlink subframes to the first mobile terminal, for each of a plurality of frames, so that none of the allocated uplink subframes overlaps in time with an allocated downlink subframe. The allocation of uplink subframes and downlink subframes is varied between consecutive ones in at least a first series of frames according to a pre-determined pattern.

Abstract: Decoding a received Orthogonal Frequency Division Multiplex (OFDM) signal that occupies a first set of subcarriers in a radio frequency spectrum includes ascertaining an interference model that represents interference occurring in the first set of subcarriers caused by a transmitted OFDM signal that occupies a second set of subcarriers in the radio frequency spectrum. A set of scaled soft values is produced that represents information conveyed by the received OFDM signal over the first set of subcarriers, wherein each scaled soft value in the set of scaled soft values corresponds to a respective one of the subcarriers in the first set of subcarriers, and wherein a scaling amount applied to each of the scaled soft values is based on a corresponding level of interference in said respective one of the subcarriers as indicated by the interference model. A decoding process is performed that generates detected data from the scaled soft values.

Abstract: An entire radio transceiver can be completely integrated into one IC chip. In order to integrate the IF filters on the chip, a heterodyne architecture with a low IF is used. A single, directly modulated VCO is used for both up-conversion during transmission, and down-conversion during reception. Bond-wires are used as resonators in the oscillator tank for the VCO. A TDD scheme is used in the air interface to eliminate cross-talk or leakage. A Gaussian-shaped binary FSK modulation scheme is used to provide a number of other implementation advantages.

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: Circuits and methods are disclosed for compensating for received signal distortion caused by non-linearities in the receiver circuitry. An exemplary receiver circuit includes a distortion waveform generator configured to approximate one or more non-linear response characteristics of a downconverter circuit used to downconvert the received radio frequency signal. The estimated distortion waveform thus produced is filtered, using a filter or filters 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 the intermediate frequency are sampled, to obtain a sampled distortion signal and a sampled signal of interest. The sampled distortion signal is scaled, and subtracted from the sampled signal of interest to obtain reduced-interference signal samples.

Abstract: An entire radio transceiver can be completely integrated into one IC chip. In order to integrate the IF filters on the chip, a heterodyne architecture with a low IF is used. A single, directly modulated VCO is used for both up-conversion during transmission, and down-conversion during reception. Bond-wires are used as resonators in the oscillator tank for the VCO. A TDD scheme is used in the air interface to eliminate cross-talk or leakage. A Gaussian-shaped binary FSK modulation scheme is used to provide a number of other implementation advantages.

Abstract: Circuits and methods are disclosed for reducing interference from transmitter leakage in a radio transceiver. An exemplary method for reducing interference from transmitter leakage in a radio transceiver comprises downconverting, filtering, and sampling a radio frequency signal comprising a desired signal and a transmitter leakage signal to obtain a sampled signal of interest. The method further comprises generating a sampled distortion signal estimate that estimates one or more distortion products of the transmitter leakage signal, such as a squared amplitude obtained from a square-law device or corresponding digital function. Further, the method comprises dividing the sampled distortion signal estimate and the sampled signal of interest into a plurality of frequency channels.

Abstract: A processing device (40) for processing an analog complex input signal generated by downconversion of an aggregated-spectrum radio-frequency signal in a radio-receiver (10), wherein the complex input signal comprises a plurality of sub bands (S1-S4) scattered across a total frequency band (4) of the complex input signal. The processing device (40) comprises a plurality of processing paths (P1-PN). wherein each processing path (P1-PN) is adapted to process an associated sub band (S1-S4). Each processing path comprises a complex mixer (CM1-CMN) adapted to frequency translate the complex input signal, and an analog channel-selection filter (CSF1-CSFN) arranged to filter an output signal of the complex mixer (CM1-CMN) and pass the frequency translated associated sub band (S1-S4). A control unit (60) is adapted to receive control data indicating frequency locations of the sub bands (S1-S4) and, for each processing path (P1-PN).

Abstract: A half-duplex mobile terminal having first and second receiver branches connected, during a receive mode, to respective antennas, is disclosed. One of the antennas is selectively connected to the first receiver branch or to a transmitter circuit. The first antenna is connected to the first receiver branch during a first interval, during which interval data is detected using outputs from both the first and second receiver branches. The first antenna is disconnected from the first receiver branch at the end of the first interval, and, during a second interval immediately following the first interval, data is detected using the output of the second receiver branch. A portion of the incoming transmission that arrives during the transition between the receive mode and transmit mode in a half-duplex transceiver is thus received and detected, improving performance of the half-duplex transceiver.

Abstract: A modulation circuit for use in a radiofrequency transmitter includes a local oscillator circuit configured to generate one or more local oscillator signals at a desired frequency and with a duty cycle at or about twenty-five percent, and a modulator configured to generate one or more modulated signals responsive to the one or more local oscillator signals and one or more baseband information signals. In at least one embodiment, the modulation circuit includes a modulator comprising a combined mixing and transconductance circuit that includes a transistor circuit for each baseband information signal serving as a modulation input to the modulator. Each transistor circuit comprises a first transistor driven by the baseband information signal and coupling a modulator output node to a corresponding transconductance element, and a second transistor driven by one of the one or more local oscillator signals and coupling the corresponding transconductance element to a signal ground node.

Abstract: A communication device has a controller operatively connected to at least a first transceiver and a second transceiver, wherein the first transceiver receives signals on one or more channels within a first frequency band and the second transceiver transmits signals on one or more channels within a second frequency band, wherein the first and second frequency bands are adjacent one another so that each of the first and second frequency bands has an adjacent border and a nonadjacent border. Coexistence between the first and second transceivers is achieved by adjusting receive and/or transmit filters associated with the transceivers to create a guard band that is located more in the first frequency band if the second transceiver is using frequencies close to its adjacent border, and a guard band that is more in the second frequency band if the second transceiver is not using frequencies close to its adjacent border.

Abstract: A digital affine transformation modulator and power amplifier drives a transmitter antenna. The modulator performs an affine transformation on a signal, wherein the I, Q space is mapped to a plurality of sectors. A signal in a sector is expressed as the sum of two vectors, the angles of which define the sector boundaries. A digital power amplifier comprises a plurality of amplifier cells, each cell comprising at least two amplifier units. For a given signal, each amplifier unit selectively amplifies a clock signal having a phase corresponding to one of the boundary angles of the signal's affine transformed sector. A subset of the plurality of amplifier cells receiving each phase clock signal are enabled, based on the magnitude of the associated vector describing the signal in affine transform space. The modulation scheme exhibits higher efficiency than quadrature modulation, without the bandwidth expansion and group delay mismatch of polar modulation.

Abstract: A delta-sigma analog-to-digital converter (ADC) is disclosed.

Abstract: A method and ASIC for canceling crosstalk between a first stereo channel and a second stereo channel, wherein a first signal is input to a first output amplifier for the first channel, and a second signal is input to a second output amplifier for the second channel, and an output load for each output amplifier is connected between each output amplifier and a reference amplifier. In one embodiment, the first and second signals are split prior to inputting the signals to the first and second output amplifiers, and a gain-adjusted portion of each signal is added to the other signal on the inputs of the output amplifiers. In another embodiment, the first and second input signals are again split into two paths each. While a first path of each signal is inputted to each signal's respective output amplifier, the second paths of the first and second signals are adding together. The resulting sum is adjusted by a gain function, biased by a suitable DC voltage, and input to the reference amplifier.

Abstract: A modulation circuit for use in a radiofrequency transmitter includes a local oscillator circuit configured to generate one or more local oscillator signals at a desired frequency and with a duty cycle at or about twenty-five percent, and a modulator configured to generate one or more modulated signals responsive to the one or more local oscillator signals and one or more baseband information signals. In at least one embodiment, the modulation circuit includes a modulator comprising a combined mixing and transconductance circuit that includes a transistor circuit for each baseband information signal serving as a modulation input to the modulator. Each transistor circuit comprises a first transistor driven by the baseband information signal and coupling a modulator output node to a corresponding transconductance element, and a second transistor driven by one of the one or more local oscillator signals and coupling the corresponding transconductance element to a signal ground node.

Abstract: A method of providing an input signal to a mixer circuit comprises coupling an output signal from a low-noise amplifier circuit to a mixer input of the mixer circuit via an AC coupling circuit, comprising an inductive of capacitive coupling circuit. For capacitive coupling configurations, a coupling capacitor is configured to have a capacitance value determined as a function of a transconductance sensitivity of the mixer circuit. For balanced output configurations of the low-noise amplifier circuit, matched coupling capacitors are used for coupling the balanced output signals to respective inputs of the mixer circuit. In one embodiment, the mixer circuit comprises a quadrature mixer circuit, which may be in a balanced or double-balanced configuration. In another embodiment, the mixer circuit comprises a four-phase mixer circuit, which may be configured as a balanced four-phase mixer circuit coupled to the low-noise amplifier circuit via inductive or capacitive embodiments of the coupling circuit.

Abstract: Circuits and methods are disclosed for reducing interference from transmitter leakage in a radio transceiver. An exemplary method for reducing interference from transmitter leakage in a radio transceiver comprises downconverting, filtering, and sampling a radio frequency signal comprising a desired signal and a transmitter leakage signal to obtain a sampled signal of interest. The method further comprises generating a sampled distortion signal estimate that estimates one or more distortion products of the transmitter leakage signal, such as a squared amplitude obtained from a square-law device or corresponding digital function. Further, the method comprises dividing the sampled distortion signal estimate and the sampled signal of interest into a plurality of frequency channels.

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.