Abstract: A transmitter includes: a decoder for transforming an IQ signal into a linear sum of two vectors which have non-negative coefficients, respectively, which form an angle of (?/4), and which are included in eight vectors representing directions indicated by eight angles of (??/2), 0, (?/2), ?, (?3?/4), (??/4), (?/4), and (3?/4), respectively, and for outputting information upon magnitudes and angles of the two vectors; a phase generator for generating eight phase signals corresponding to phases of (??/2), 0, (?/2), ?, (?3?/4), (??/4), (?/4), and (3?/4), respectively, and outputting the eight phase signals; and a selector for selecting two phase signals having phases equivalent to angles of the two vectors, from among the eight phase signals, and amplifying the two phase signals having been selected, based on the information upon the magnitudes and the angles, and outputting, as a plurality of amplification signals, the two phase signals having been amplified.

Abstract: A transmission circuit that performs modulation based on a phase difference signal and an amplitude signal includes an asymmetrical phase rotation device. The asymmetrical phase rotation device performs an operation of subtracting 2? from a value of the phase difference signal when the value of the phase difference signal is greater than a predetermined positive threshold value, or an operation of adding 2? to the value of the phase difference signal when the value of the phase difference signal is less than a predetermined negative threshold value. Accordingly, the transmission circuit has distortion reduction characteristics improved uniformly over a range of frequencies higher or lower than a carrier wave band.

Abstract: A communications transmitter configured to reduce the average-to-minimum magnitude ratio (AMR) of a communications signal includes a symbol mapper, a pulse-shaping filter, an AMR reduction circuit, and a modulator. The symbol mapper operates to generate a sequence of symbols from a binary-source data stream containing a message to be transmitted, and the pulse-shaping filter generates a baseband signal based on the sequence of symbols. The AMR reduction circuit is configured to compare a magnitude of a local minimum of samples of the baseband signal to various magnitude threshold levels, and to modify the baseband signal in one of two manners depending on the relationship of the magnitude of the local minimum and the various threshold levels. Finally, the modulator operates to modulate a carrier signal based on the modulation information contained in the modified baseband signal.

Abstract: A transmitter includes: a decoder for transforming an IQ signal into a linear sum of two vectors which have non-negative coefficients, respectively, which form an angle of (?/4), and which are included in eight vectors representing directions indicated by eight angles of (??/2), 0, (?/2), ?, (?3?/4), (??/4), (?/4), and (3?/4), respectively, and for outputting information upon magnitudes and angles of the two vectors; a phase generator for generating eight phase signals corresponding to phases of (??/2), 0, (?/2), ?, (?3?/4), (??/4), (?/4), and (3?/4), respectively, and outputting the eight phase signals; and a selector for selecting two phase signals having phases equivalent to angles of the two vectors, from among the eight phase signals, and amplifying the two phase signals having been selected, based on the information upon the magnitudes and the angles, and outputting, as a plurality of amplification signals, the two phase signals having been amplified.

Abstract: A nonlinear filter includes: a determination unit that determines, based on I and Q signals inputted into the determination unit, whether or not to perform pulse insertion; a rotation detector that detects a rotation direction of the I and Q signals on an IQ plane with respect to the origin of the IQ plane; a pulse generator that generates, when the determination unit determines to perform the pulse insertion, a pulse of which at least one of the direction and the magnitude is determined in accordance with at least the detected rotation direction; and an adder that inserts the pulse into the I and Q signals and outputs resultant I and Q signals.

Abstract: A polar modulation transmitter includes an amplitude modulation (AM) path with an amplitude modulation to amplitude modulation (AM/AM?) correction circuit and a phase modulation (PM) path with a delay element and an amplitude modulation to phase modulation (AM?/PM) correction circuit. The AM/AM? correction circuit receives and predistorts a digital amplitude component signal depending on amplitudes of samples in the digital amplitude component signal, thereby generating a predistorted digital amplitude component signal. The delay element receives and delays a digital phase component signal, to generate a delayed digital phase component signal having a delay corresponding to the latency introduced by the AM/AM? correction circuit. The AM?/PM correction circuit predistorts the delayed digital phase component signal depending on amplitudes of samples in the predistorted amplitude component signal, thereby generating a predistorted digital phase component signal.

Abstract: Methods and apparatus for controlling events, timing and operational characteristics of wireless communications devices. An exemplary wireless communications apparatus comprises a baseband processor, radio frequency (RF) generating circuitry, a programmable event controller, and a memory device. The RF generating circuitry and programmable event controller are integrated in the same integrated circuit. The memory device, which may also be embedded in the same integrated circuit as the event controller and RF generating circuitry, is configured to store a sequence of instructions the event controller executes in response to a baseband command. The memory device is also configured to store control parameter data, which the event controller retrieves and uses to enable, disable, select and deselect various devices on the integrated circuit and to set, adjust or modify the operational characteristics of the RF generating circuitry (e.g., band selection and tuning) and other circuitry (e.g.

Abstract: Methods and apparatus for predistorting signals in a polar modulation transmitter. An exemplary method includes predistorting an envelope component signal in an amplitude path of a polar modulation transmitter according to a set of AM/AM predistortion coefficients, and predistorting a phase component signal in a phase path of the polar modulation transmitter according to a set of AM/PM predistortion coefficients. The AM/AM and AM/PM predistortion coefficients are stored in a memory in the form of a look up table (LUT). The envelope component signal is scaled and/or offset, before predistortion is applied, by an amount dependent upon which average power level of a plurality of average power levels the power amplifier of the polar modulation transmitter is configured to operate. Scaling and/or offsetting the envelope component signal prior to applying predistortion affords the ability to share the AM/AM and AM/PM predistortion coefficients of the predistortion LUT over the plurality of average power levels.

Abstract: A nonlinear filter includes: a determination unit that determines, based on I and Q signals inputted into the determination unit, whether or not to perform pulse insertion; a rotation detector that detects a rotation direction of the I and Q signals on an IQ plane with respect to the origin of the IQ plane; a pulse generator that generates, when the determination unit determines to perform the pulse insertion, a pulse of which at least one of the direction and the magnitude is determined in accordance with at least the detected rotation direction; and an adder that inserts the pulse into the I and Q signals and outputs resultant I and Q signals.

Abstract: A transmission circuit that performs modulation based on a phase difference signal and an amplitude signal includes an asymmetrical phase rotation device. The asymmetrical phase rotation device performs an operation of subtracting 2? from a value of the phase difference signal when the value of the phase difference signal is greater than a predetermined positive threshold value, or an operation of adding 2? to the value of the phase difference signal when the value of the phase difference signal is less than a predetermined negative threshold value. Accordingly, the transmission circuit has distortion reduction characteristics improved uniformly over a range of frequencies higher or lower than a carrier wave band.

Abstract: Methods and apparatus for reducing the bandwidth of modulation signals in a phase path of a polar modulation transmitter. An exemplary method includes generating a phase difference modulation signal for a phase path of a polar modulation transmitter, and filtering the phase difference modulation signal using a linear-phase filter. Filtering the phase difference modulation signal may be performed by first detecting samples in the phase difference modulation signal that have phase difference values in excess of a phase difference threshold and then filtering samples in the vicinity of the threshold-violating samples to remove the threshold-violating events. Alternatively, all samples may be filtered, i.e., without regard as to whether any given sample exceeds a phase difference threshold, to remove large phase difference changes in the phase difference modulation signal, or a combination of linear-phase and nonlinear filters may be used to remove the large phase difference changes.

Abstract: Methods and apparatus for reconstructing discrete-time amplitude modulation signals in polar modulation transmitters. An exemplary polar modulation transmitter includes a symbol generator, a rectangular-to-polar converter, a peak phase detector, and an amplitude modulation reconstruction circuit. The symbol generator generates rectangular-coordinate modulation symbols from which the rectangular-to-polar converter generates an amplitude modulation signal containing discrete-time amplitude samples and an angle modulation signal containing discrete-time angle samples. The peak phase detector circuit detects phase reversals or near phase reversals represented in samples of the angle modulation signal. The amplitude modulation reconstruction circuit responds by reconstructing samples in the amplitude modulation signal that correspond to detected phase reversals or a near phase reversals represented in samples of the angle modulation signal.

Abstract: A frequency modulator capable of performing frequency modulation without increasing quantization noise; and a method for adjusting the gain thereof are provided. An input signal is gain-adjusted by a gain adjustment section and outputted to a frequency modulation section. The frequency modulation section is gain-controlled based on a first signal. For setting a digital gain coefficient and an analog gain coefficient of the gain adjustment section, a test signal is inputted. In this state, in a generation section, first control information for setting the digital gain coefficient and second control information for setting the analog gain coefficient are generated based on information regarding a state of the frequency modulation section.

Abstract: A communications transmitter configured to reduce the average-to-minimum magnitude ratio (AMR) of a communications signal includes a symbol mapper, a pulse-shaping filter, an AMR reduction circuit, and a modulator. The symbol mapper operates to generate a sequence of symbols from a binary-source data stream containing a message to be transmitted, and the pulse-shaping filter generates a baseband signal based on the sequence of symbols. The AMR reduction circuit is configured to compare a magnitude of a local minimum of samples of the baseband signal to various magnitude threshold levels, and to modify the baseband signal in one of two manners depending on the relationship of the magnitude of the local minimum and the various threshold levels. Finally, the modulator operates to modulate a carrier signal based on the modulation information contained in the modified baseband signal.

Abstract: A frequency modulator capable of performing frequency modulation without increasing quantization noise; and a method for adjusting the gain thereof are provided. An input signal is gain-adjusted by a gain adjustment section and outputted to a frequency modulation section. The frequency modulation section is gain-controlled based on a first signal. For setting a digital gain coefficient and an analog gain coefficient of the gain adjustment section, a test signal is inputted. In this state, in a generation section, first control information for setting the digital gain coefficient and second control information for setting the analog gain coefficient are generated based on information regarding a state of the frequency modulation section.

Abstract: Sampled IQ values at the origin are revalued by applying a minimum distance, or radius, away from the (0,0) coordinate in the IQ domain, and applying a rotation about the origin for consecutive (0,0) samples, thereby improving communication performance. A direction of rotation is able to be predetermined or dynamically determined according to a correction look-up table or an IQ trajectory.

Abstract: Embodiments of a multi-point push-out method are disclosed for a more accurate adjustment of minimum IQ values in order to maintain better continuity in the IQ trajectory for sampled IQ values near the origin. IQ trajectories near the origin are limited to a minimum IQ value by determining a specific scaling factor according to a position of the sampled IQ value relative to the origin and/or to the minimum IQ value. The minimum IQ value is also referred to as a threshold boundary value.

Abstract: A self-calibrating modulator apparatus includes a modulator having a controlled oscillator and an oscillator gain calibration circuit. The oscillator gain calibration circuit includes an oscillator gain coefficient calculator configured to calculate a plurality of frequency dependent oscillator gain coefficients from results of measurements taken at the output of the controlled oscillator in response to a test pattern signal representing a plurality of different reference frequencies. The plurality of frequency dependent gain coefficients determined from the calibration process are stored in a look up table (LUT), where they are made available after the calibration process ends to scale a modulation signal applied to the modulator. By scaling the modulation signal prior to it being applied to the control input of the controlled oscillator, the nonlinear response of the controlled oscillator is countered and the modulation accuracy of the modulator is thereby improved.

Abstract: A polar modulation transmitter includes an amplitude modulation (AM) path with an amplitude modulation to amplitude modulation (AM/AM?) correction circuit and a phase modulation (PM) path with a delay element and an amplitude modulation to phase modulation (AM?/PM) correction circuit. The AM/AM? correction circuit receives and predistorts a digital amplitude component signal depending on amplitudes of samples in the digital amplitude component signal, thereby generating a predistorted digital amplitude component signal. The delay element receives and delays a digital phase component signal, to generate a delayed digital phase component signal having a delay corresponding to the latency introduced by the AM/AM? correction circuit. The AM?/PM correction circuit predistorts the delayed digital phase component signal depending on amplitudes of samples in the predistorted amplitude component signal, thereby generating a predistorted digital phase component signal.

Abstract: An exemplary modulator apparatus for a polar modulation transmitter includes a phase difference extractor, a phase modulator, and a coarse phase controller. The phase difference extractor is configured to extract +180° and ?180° phase differences represented in a phase-difference modulation signal in a phase modulation path of the polar modulation transmitter, or extract other phase differences exceeding other predetermined phase difference thresholds, to produce a bandwidth-reduced phase-difference modulation signal. The phase modulator includes a controlled oscillator having a tuning port that is modulated by phase differences represented in the bandwidth-reduced phase-difference modulation signal, to produce a phase-modulated RF carrier signal. The coarse phase controller operates to effectuate phase reversals or introduce other coarse phase changes into the phase-modulated RF carrier signal, based on the phase differences extracted from the original phase-difference modulation signal.