Patent application number | Description | Published |
20080219331 | Methods and apparatus for reducing the effects of DAC images in radio frequency transceivers - 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. | 09-11-2008 |
20080246550 | Selective envelope modulation enabling reduced current consumption - 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. | 10-09-2008 |
20090011730 | Methods and Apparatus for Controlling Power in a Polar Modulation Transmitter - 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. | 01-08-2009 |
20090176464 | Multiple-mode modulator to process baseband signals - A multiple-mode modulator is configured similarly to a direct conversion quadrature modulator with an infusion of an amplitude modulation signal path from a large signal polar modulator to improve the power amplifier efficiency. The multiple-mode modulator also includes a radio frequency signal path. The multiple-mode modulator is configured to receive a baseband signal, convert the baseband signal to a radio frequency (RF) signal, and to process the RF signal according to either a polar mode or a quadrature mode, depending on a time-varying input voltage of the RF signal. When the power amplifier operates in the linear region, the RF signal is processed according to the quadrature mode. When the power amplifier operates in the compressed region, the RF signal is processed according to the polar mode. The multiple-mode modulator can be configured according to a small signal polar architecture or a large signal polar architecture, having either an open-loop or closed-loop configuration. | 07-09-2009 |
20090191826 | High-Efficiency Envelope Tracking Systems and Methods for Radio Frequency Power Amplifiers - Envelope tracking (ET) methods and systems for controlling the delivery of power to radio frequency power amplifiers (RFPAs). An exemplary ET system includes an RFPA and a wide bandwidth capable and power efficient envelope modulator that includes a first power supplying apparatus and a second power supplying apparatus. The first power supplying apparatus includes a switch-mode converter and a regulator. The first mode converter is operable to dynamically step down a fixed power supply voltage according to amplitude variations in an envelope signal received by the regulator, and use the resulting dynamic power supply signal to power the regulator. The second power supplying apparatus is connected in parallel with the first power supplying apparatus. Depending on a power of an output signal to be generated at an output of the power amplifier, power is supplied to the power amplifier from either or both of the first and second power supplying apparatuses. | 07-30-2009 |
20090257526 | METHODS AND APPARATUS FOR CONDITIONING COMMUNICATIONS SIGNALS BASED ON DETECTION OF HIGH-FREQUENCY EVENTS IN POLAR DOMAIN - Methods and apparatus for conditioning communications signals based on detection of high-frequency in the polar domain. High-frequency events detected in a phase-difference component of a complex baseband signal in the polar domain are detected and used as a basis for performing hole-blowing on the complex baseband signal in the quadrature domain and/or nonlinear filtering either or both the magnitude and phase-difference components in the polar domain. Alternatively, high-frequency events detected in the phase-difference signal that correlate in time with low-magnitude events detected in a magnitude component of the complex baseband signal are used as a basis for performing hole-blowing on the complex baseband signal in the quadrature domain and/or nonlinear filtering either or both the magnitude and phase-difference components in the polar domain. | 10-15-2009 |
20090289720 | High-Efficiency Envelope Tracking Systems and Methods for Radio Frequency Power Amplifiers - High-efficiency envelope tracking (ET) methods and apparatus for dynamically controlling power supplied to radio frequency power amplifiers (RFPAs). An exemplary ET circuit includes a switch-mode converter coupled in parallel with a split-path linear regulator. The switch-mode converter is configured to generally track an input envelope signal Venv and supply the current needs of a load (e.g., an RFPA). The split-path linear regulator compensates for inaccurate envelope tracking by sourcing or sinking current to the load via a main current path. A current sense path connected in parallel with the main current path includes a current sense resistor used by a hysteresis comparator to control the switching of the switch-mode converter. The split-path linear regulator is configured so that current flowing in the current sense path is a lower, scaled version of the current flowing in the main current path. | 11-26-2009 |
20100015932 | SIGNAL DECOMPOSITION METHODS AND APPARATUS FOR MULTI-MODE TRANSMITTERS - A multi-mode communications transmitter includes a signal decomposer that converts rectangular-coordinate in-channel and quadrature channel signals into polar-coordinate amplitude and angle component signals and form therefrom first and second modulation signals. The signal decomposition process performed by the signal decomposer combines envelope-reduction and restoration (ERR) with filtering to reduce the bandwidths of the first and second modulation signals compared to the bandwidths of the unmodified amplitude and angle component signals. The reduction in signal bandwidths eases the design requirements of the electrical components needed to process and generate the signals applied to the power supply and radio frequency (RF) input ports of the multi-mode communications transmitter's power amplifier (PA). It also makes the multi-mode communications transmitter more forgiving to gain and delay mismatches between the signals applied to the power supply and RF input ports of the PA, compared to conventional polar modulation transmitters. | 01-21-2010 |
20100027725 | NOISE-CANCELING FREQUENCY-TO-DIGITAL CONVERTERS - Methods and apparatuses for reducing noise in frequency to digital converters (FDCs). An FDC apparatus includes a first FDC, a second FDC and a combiner. The first and second FDCs are configured to independently sample an input signal according to a sample clock to generate first and second digital signals, each representing the instantaneous frequency of the input signal. The combiner is configured to form a resultant digital signal from the first and second digital signals. The first and second FDCs are designed and combined in the noise-canceling FDC apparatus so that the first and second signals they generate have correlated noise profiles in a frequency range of interest. When combined by the combiner to form the resultant digital signal, the resultant digital signal has a signal power to noise power ratio greater than the signal power to noise power ratios characterizing the first and second digital signals of the individual first and second FDCs. | 02-04-2010 |
20100056068 | MULTI-MODE TRANSMITTER HAVING ADAPTIVE OPERATING MODE CONTROL - Methods and apparatus for transmitting communications signals that are both power efficient and effective at avoiding or reducing transmitter-generated receive band noise. An exemplary transceiver apparatus includes a multi-mode transmitter that is configurable to operate in a plurality of operating modes (e.g., a polar mode, a quadrature mode and a hybrid mode), a receiver, and an operating mode controller. The operating mode controller is configured to control which operating mode the transmitter is to operate, depending on one or more of a transmit (Tx) power, receive (Rx) power, the Tx power relative to the Rx power, a level of frequency separation between a Tx frequency band and a Rx frequency band (Tx/Rx band separation), and modulation type employed by the transmitter. | 03-04-2010 |
20100069025 | HIGH-EFFICIENCY TRANSMITTER WITH LOAD IMPEDANCE CONTROL - A transmitter generates first and second constant-envelope radio frequency (RF) component signals having first and second phase angles. The first and second phases are controlled by a phase controller. First and second nonlinear power amplifiers (PAs) are modulated by an amplitude-modulated power supply signal as the first and second constant-envelope RF component signals are amplified. The phase controller controls the first and second phases of the first and second constant-envelope RF component signals, in response to a power control signal, and, in so doing, controls an effective load impedance seen at the outputs of the first and second nonlinear PAs. By controlling the effective load impedance in response to a power control signal, rather than in response to rapid amplitude variations in an input signal envelope, the output power of the transmitter is efficiently controlled over a wide dynamic range even at low output powers. | 03-18-2010 |
20100246716 | METHODS AND APPARATUS FOR REDUCING HIGH-FREQUENCY EVENTS IN POLAR DOMAIN SIGNALS - Methods and apparatus for reducing high-frequency events in polar domain signals. An exemplary method includes first generating an unmodified rectangular-coordinate signal having in-phase (I) and quadrature phase (Q) components that are modulated according to a predetermined modulation scheme. Next a first sample of the unmodified rectangular-coordinate signal is modified based on how close the first sample is to the origin in the complex signal plane and how fast a signal trajectory between the first sample and a subsequent sample changes. Finally, the modified rectangular-coordinate signal is converted to a polar domain signal having amplitude and phase components. By modifying the first sample in this manner, either or both the amplitude and phase components have reduced high-frequency content compared to a polar domain signal that would be generated without the first sample having been first modified. | 09-30-2010 |
20100301953 | PHASE LOCK LOOP WITH A MULTIPHASE OSCILLATOR - A phase lock loop utilizes a multiphase oscillator having a plurality of digital inputs. A plurality of DQ flip-flops, offset in time from each other generate a plurality of control signals to remove control phase information from the oscillator in digital form. A DQ flip-flop connected between any two digital inputs on the oscillator determines direction of the traveling wave. The direction and phase information address a look-up table to determine the current fractional phase of the oscillator. A divide by N circuit is used to reduce the oscillator frequency. A total phase indicator signal for the oscillator is determined using the current fractional phase. The total phase is compared to a reference phase to produce a control signal for making adjustments to the oscillator. In a feed-forward path, frequency dividers divide a high frequency signal from the oscillator to a lower desired frequency, thereby increasing phase resolution. | 12-02-2010 |
20100303135 | METHOD AND APPARATUS FOR DIRECT RF TO DIGITAL CONVERTER - The invention relates to a method and apparatus for decomposing a high frequency incoming signal into several low frequency signals without the loss of any information. The low frequency signals can define a plurality of digital data streams. The decomposing steps are implemented without processing the signal through a mixer or a local oscillator and without degrading the SNR. In a preferred embodiment, a decomposing circuit includes a single-to-differential converter for decomposing the incoming high frequency signal into a first and a second signal having opposite polarity. Each of the first and the second incoming signals is then processed through multistage cascading logic units which reduce the frequency of the respective signals to provide a plurality of low-frequency data streams. The resulting slow-speed data streams are combined to form a low-speed data stream containing all the information provided by the original high-frequency signal. | 12-02-2010 |
20100316164 | Methods and Apparatus for Reducing Average-to-Minimum Power Ratio in Communications Signals - A baseband circuit for a communications transmitter includes a baseband modulator, a pulse-shaping filter, and an AMPR reduction circuit. The baseband modulator is configured to generate a sequence of symbols formatted in accordance with a non-constant envelope modulation scheme. The pulse-shaping filter is configured to band-limit the sequence of samples to provide a sequence of samples. The AMPR reduction circuit is configured to analyze and modify one or more samples in the sequence of samples, if a sample in the sequence of samples that has been previously analyzed by the AMPR reduction circuit is determined to have a magnitude less than a predetermined low-magnitude threshold. | 12-16-2010 |
20110018640 | TRANSMITTER UTILIZING A DUTY CYCLE ENVELOPE REDUCTION AND RESTORATION MODULATOR - A broad power band transmitter utilizing a duty cycle modulator achieves 80dB of power range for 3G signals. The present invention greatly improves the efficiency of transmitters used in mobile phones, for example, by using the duty cycle modulator during medium and low power levels of the transmitting power amplifier. The power amplifier operates in three different modes based upon the amplifier power level selected. The power amplifier operates in an EER mode during high power levels, in a DCM ERR mode during medium power levels, and in a DCM mode during low power levels. | 01-27-2011 |
20110058622 | METHOD AND APPARATUS FOR PROVIDING HIGH EFFICIENCY CARTESIAN MODULATION - The disclosure relates to a method and apparatus for providing efficient signal transmission. Conventional linear amplifiers are most efficient when operated in compressed mode. In the compressed mode, the digital power amplifier switches between the on and off modes. A digital power amplifier operates in compressed mode only if the incoming signal is an on-off constant envelop signal. In one embodiment, the disclosure provides a method and apparatus for converting a digital baseband signal to on-off constant envelop signals for processing through binary-weighted or thermometer-weighted amplifier which are operated in compressed mode. | 03-10-2011 |
20110075755 | MULTIPHASE DIRECT RF FREQUENCY TO DIGITAL CONVERTER AND RELATED METHOD - The disclosure provides an effective means for fine-resolution determination of the frequency content of an RF signal using low speed digital circuits. The disclosure relates to a method and apparatus for decomposing a high frequency RF signal into several low frequency signals or data streams without loss of any information and without the use of extraneous circuit components such as local oscillators, mixers or offset phase-locked loops. Single or multiple phase oscillator outputs are fed directly to a single or multiple direct RF frequency-to-digital (DrfDC) circuits. The front end of the DrfDC circuit decomposes a high frequency signal into several low frequency signals without loss of any information. The low frequency signals are processed by the back-end of the DrfDC and converted into digital data streams. The digital data streams are then combined and averaged to represent the frequency of the input RF signal. | 03-31-2011 |
20110176636 | HIGH-EFFICIENCY ALL-DIGITAL TRANSMITTER - A low cost high-efficiency all-digital transmitter using all-digital power amplifiers (“DPA”) and various mapping techniques to generate an output signal, which substantially reproduces a baseband signal at a carrier frequency. A baseband signal generator generates a baseband signal which is quantized by a signal processor using a quantization map. A DPA control mapper outputs control signals to phase selectors using the quantized signal and a quantization table. Each phase selector receives one of the control signals and outputs a waveform at a carrier frequency with a phase corresponding to the control signals, or an inactive signal. Each DPA in a DPA array has an assigned weight, receives one of the waveforms from the phase selectors, and outputs a power signal according to the weight of the DPA and the phase of the received waveform. The combined power signal substantially reproduces the baseband signal at the carrier frequency. | 07-21-2011 |