Abstract: The signal-to-noise ratio for a digital conversion circuit is improved by taking a source signal and generating N signals that are each phase-shifted relative to each other, thereby generating N phase-shifted signals. Each of the N signals has a frequency that is a fraction of a frequency of the source signal. The source signal is input to a dividing circuit to generate the N signals. The source signal is generated by a signal source, such as an oscillator. Each of the N signals is hard-limited and processed through a detection circuit. The detection circuit can be a frequency detection circuit configured to determine the frequency of the source signal and to output a corresponding digital word, or a phase detection circuit configured to determine a phase of the source signal and to output a corresponding digital word.

Abstract: A power amplifier of a polar transmitter having separate amplitude and phase paths is configured so that its output power is controlled by power control circuitry disposed in both the amplitude and phase paths of the transmitter. Coarse power control is provided by coarse power control circuitry configured in the phase path. Fine power control is performed by digital power control circuitry configured in the amplitude path. The combined coarse power control circuitry in the phase path and digital power control circuitry in the amplitude path allows the output power of the power amplifier to be controlled at the accuracy and resolution required by wireless communications standards such as, for example, the W-CDMA standard.

Abstract: A modulation system includes an amplitude modulation path and a phase modulation path coupled to the amplitude modulation path. One of the amplitude modulation path and the phase modulation path receive a reduced current such that the reduced current reduces power consumption by the system. Preferably, the amplitude modulation path receives the reduced current. The amplitude modulation path has a first set of components and a second set of components. The first set of components consumes less power by using slower operation. The second set of components consumes less power by effectively not operating, or being turned off.

Abstract: A transmitter has a signal generator, an amplifier, a detection circuit, a comparison circuit, a loop filter, and an adjustable clock. The signal generator produces a signal. The signal is produced with a first frequency characteristic and contains frequency-related information. The detection circuit detects the first frequency-related characteristic and generates an associated signal in response. A comparison circuit compares the signal from the detection circuit and another signal. It outputs a signal associated with the difference between the two. A loop filter receives the output of the comparison circuit and generates a signal to the signal generator in. The loop filter is clocked at a second frequency by a signal from a clock circuit. The clock circuit can compare the first frequency and the second frequency, and can change the second frequency based upon a relationship between the two frequencies.

Abstract: Methods and apparatus for reducing the effects of digital-to-analog converter (DAC) images and transmission spurious effects in a receive frequency band of a radio frequency (RF) transceiver. A transceiver apparatus includes a transmitter portion having a DAC, a receiver portion configured to receive RF signals in a receive frequency band, and a variable rate clock generator. The variable rate clock generator is used to provide an oversampling clock for the DAC. The rate of the oversampling clock is adjustable and is selected so that an upconverted version of a DAC image created by the DAC is steered away from frequencies within the receive frequency band. A notch-effect low-pass filter (NELPF) may also, or alternatively, be used in the transceiver to reduce transmission spurious effects in the receive frequency band.

Abstract: A method of determining a gain nonlinearity receives a phase difference and generates an output frequency based on the received phase difference. The method reconstructs a waveform by using the output frequency. The method preprocesses the phase difference to generate a comparison waveform. The method compares the reconstructed waveform to the comparison waveform and determines a gain nonlinearity based on the comparison between the reconstructed and comparison waveforms. A modulation system includes a voltage controlled oscillator for receiving an input signal based on a phase difference and generating an output frequency. The system further includes a waveform reconstructor and a comparator. The waveform reconstructor is coupled to the voltage controlled oscillator, and is for reconstructing a waveform based on the output frequency. The comparator is coupled to the waveform reconstructor, and is for comparing the output of the waveform reconstructor with the input signal.

Abstract: Methods and apparatus for optimizing pulses provided by a pulse-shaping filter implemented in hardware. Pulses are optimized and generated by the pulse-shaping filter that are of finite length and meet one or more signal quality criteria, e.g., error vector magnitude (EVM) and/or adjacent channel leakage ratio (ACLR). According to one exemplary embodiment, a first finite length constraint is identified and a second out-of-band power criterion is identified. An error function is defined which measures the distortion of the generated signal relative to a reference pulse modeled after an ‘ideal’ pulse. The error function is minimized to determine optimized pulses, which when used to pulse-shape a communications signal, do not substantially increase in-channel distortion of said communications signal. To avoid the generation of excessive out-of-channel power, minimization is performed subject to a predetermined maximum allowable out-of-channel power condition.

Abstract: Methods and apparatus for conditioning low-magnitude events in electrical signals. According to an exemplary method, a low-magnitude event occurring in a signal trajectory of a received electrical signal is analyzed. The low-magnitude event is defined by a data point on a signal trajectory having a magnitude that is less than a predetermined signal magnitude minimum. A correction impulse having a correction magnitude and a correction phase is generated based on the magnitude and phase of data points on the signal trajectory that occur prior to and after the occurrence of the low magnitude event. The correction impulse is combined with the original electrical signal in the temporal vicinity of the low-magnitude event, thereby generating a corrected electrical signal having a more controlled bandwidth.

Abstract: A device for transmitting information in a communications signal is envisioned. The information is modulated, at least in part, with a first angle-related characteristic. The device has a digital conversion circuit operable to convert information to be broadcast into a digital form. A constellation mapper is coupled to the digital conversion circuit, and is operable to convert the digital information into information associated with a constellation. A trajectory generation circuit generates samples denoting a trajectory within the constellation for the information. A transition analysis circuit determines a change in value of an angle-related characteristic in a transition between two samples, and a threshold detection circuit detects whether the change in value fails to meet a particular threshold. An angle-related characteristic distribution circuit can then distribute a portion of the change in value associated with the transition to at least one other transition.

Abstract: This invention, generally speaking, modifies pulse amplitude modulated signals to reduce the ratio of average power to minimum power. The signal is modified in such a manner that the signal quality remains acceptable. The signal quality is described in terms of the Power Spectral Density (PSD) and the Error Vector Magnitude (EVM).