摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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).
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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. The comparator is configured for determining a gain nonlinearity exhibited by the voltage controlled oscillator. Particular embodiments further include a compensator.