70 results about "Nonlinear power amplifier" patented technology

A system and a method are provided. The system may include (A) a measurement circuit arranged to measure at least a current power level of the input signal; (B) multiple non-linear power amplifiers; wherein different non-linear power amplifiers are associated with different power ranges; (C) a control circuit arranged to: (a) select at least one selected non-linear power amplifier to be used to amplify a second signal based on at least: (i) the current power level of an input signal; (ii) an association between the different power ranges and the different non-linear power amplifiers; (iii) an identity of at least one previously selected non-linear power amplifier; and (b) assist in an activation of the at least one selected non-linear power amplifier; and (D) a signal processing module, configured to process the input signal to provide the second signal such as to at least partially compensate for a non-linearity of each of the at least one selected non-linear power amplifier.

The present invention relates to a predistortion signal amplifier arrangement comprising digital predistortion means for predistortion of an input signal, a non-linear power amplifier, a predistortion control arrangement comprising error estimation means for estimating the error produced in the predistorted signal and a predistortion look-up table arrangement, the content in which is updated by the estimation means. The predistortion look-up table arrangement comprises at least two look-up tables, which are updated by said estimation means and said at least two look-up tables have different number of table entries. It further comprises a combiner for combining updated values obtained from said at least two look-up tables into a composite value and said composite value comprises a distortion coefficient which is input to said digital predistortion arrangement for signal predistortion.

An apparatus for improving linearity of an RF signal comprising: (a) a splitter configured to receive an input RF signal, and configured to split the input RF signal into two RF signals comprising a first input RF signal, and a second input RF signal; (b) an over-biased non-linear RF power amplifier configured to receive the first input RF signal and configured to generate an over-biased non-linear output signal having an over-biased non-linear distortion component; (c) an under-biased non-linear RF power amplifier configured to receive the second input RF signal and configured to generate an under-biased non-linear output signal having an under-biased non-linear distortion component; and (d) a combiner configured to combine the over-biased non-linear output signal and the under-biased non-linear output signal, and configured to output the RF signal having substantially cancelled over-biased and under-biased distortion components. The over-biased non-linear RF power amplifier is configured to receive an over-biased DC signal being greater than an optimum bias DC voltage. The under-biased non-linear RF power amplifier is configured to receive an under-biased DC signal being lower than the optimum bias DC voltage.

A apparatus linearizing and technique for linearizing a non-linear power amplifier used in a transmitter of, e.g., a TDMA mobile wireless telephone. Linearization of the non-linear amplifier by changing the shape of the input signal is performed when the input signal level is high, thus increasing efficiency or reducing power consumption at that time, albeit at the cost of increased inter-symbol interference (ISI). However, since the input signals at that time are at a high level, the increased ISI can be tolerated and adjacent symbols can still be distinguished from one another. The invention allows use of a non-linear power amplifier which typically enjoys a lower current consumption than that of a linear power amplifier, thus increasing the time between battery recharges and / or reducing the overall size of the wireless telephone device. The power amplifier is operated in a linear mode when transmitted power is low, thus allowing differentiation between adjacent symbols (i.e., improvement of ISI). At high input power, the power amplifier is used in its non-linear mode to reduce current consumption. The signal shape is changed by changing the parameters of the root raised cosine filters. When the input level is low, the existing, otherwise conventional filter's parameters are used. However, when the input power level is high, modified parameters are used. Switching between the two sets of filter parameters is preferably performed at baseband. Thus, a relationship between RRCF filter parameters and the amount of spectrum utilized by the transmitted signal is utilized, and RRCF filter parameters are adjusted based on a desired limitation to an output spectrum.

Methods and systems for polar modulation using a digital direct frequency synthesizer (DDFS) are disclosed and may comprise generating a phase modulated signal in a DDFS, amplitude modulating the generated phase modulated signal in a non-linear device and transmitting the signal via a wireless medium. A processor may control the generation of the phase and amplitude modulated signals. The non-linear device may comprise a non-linear power amplifier or a mixer. The method may also comprise generating a first phase modulated signal in a first DDFS and generating a second phase modulated signal in a second DDFS, or in a single DDFS with two integrated digital-to-analog converters, and upconverting and combining the first and second phase modulated signals and amplitude modulating the combined upconverted signals in a non-linear device. A processor may be enabled to control the generation of the first and second phase modulated signals.

The invention relates to amplitude and phase control equipment and an amplitude and phase control method for a power amplifier. The phase and amplitude of the amplifier are randomly regulated by adopting the symmetric phase control of a pair of synthesis branches in the amplifier, so that the limitations of the power handing level of an attenuator to the overall attenuator for the amplitude and phase control of the power amplifier are broken. By the technology, the problems of limitations of the power handing level of the attenuator to the attenuator in the amplitude and phase control of the power amplifier, particularly a nonlinear power amplifier are solved, and the amplitude and phase of any type of amplifier with any high-power output can be controlled.

The invention relates to a power amplifier, in particular to a low nonlinear distortion power amplifier. The low nonlinear distortion power amplifier comprises a main power amplifier, a distortion signal generator, a distortion signal amplifier, a first coupling, a second coupling, an attenuator and a phase shifter, wherein the main power amplifier amplifies a radio frequency input signal A, and attenuates and reverses a bypass radio frequency input signal which is coupled simultaneously, a signal which is reversed with a third-order intermodulation distortion signal which is generated by the main power amplifier is generated by the distortion signal generator, the distortion signal which is amplified is coupled with an output signal of the main power amplifier, which enables the third-order intermodulation distortion signal which is generated by the main power amplifier to be counteracted with the distortion signal which is generated by the distortion signal amplifier, and has equiamplitude and is reversed with the third-order intermodulation distortion signal which is generated by the main power amplifier, and finally an ideal radio frequency power amplifying signal is obtained. The invention has the advantages of excellent performance, high efficiency, simple structure and low cost, and can be used in various systems which need to use linearized power amplifiers.

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.

An electronic device includes a nonlinear power amplifier, a predistortion coefficient calculator, and a memory polynomial predistortion filter coupled to the nonlinear power amplifier and to the predistortion coefficient calculator. The memory polynomial predistortion filter may include a plurality of finite impulse response (FIR) filter stages, and a summer coupled to the plurality of FIR filter stages. The FIR filter stages may functionally operate in parallel or may include a series of FIR filters coupled in parallel.

The invention relates to a system and method for inhibiting an OFDM peak-to-average ration by combining pulse shaping with digital pre-distortion. For the problem that the OFDM signal high peak-to-average ratio produces serious nonlinear distortion and transmission signal spectrum diffusion in a nonlinear transmitting channel, on the one hand, the high PAPR of the OFDM is reduced by using the phase shaping technology starting from the signal construction of the OFDM; on the other hand, the linear range of a power amplifier is improved by using the self-adaptive digital pre-distortion technology starting from the nonlinear power amplifier performance, therefore, a method of combining the pulse shaping technology with the self-adaptive digital pre-distortion technology is proposed, the requirement on the transmitting channel linearity by the high PAPR of the OFDM signal is reduced; a simulation result shows that the PAPR of the OFDM signal is small, the power amplifier linear range is large, so that the transmitting power of the signal can be increased, the signal-to-noise ratio of the system is indirectly improved,, thereby effectively improving the system performance.

Methods and systems for polar modulation using a digital direct frequency synthesizer (DDFS) are disclosed and may comprise generating a phase modulated signal in a DDFS, amplitude modulating the generated phase modulated signal in a non-linear device and transmitting the signal via a wireless medium. A processor may control the generation of the phase and amplitude modulated signals. The non-linear device may comprise a non-linear power amplifier or a mixer. The method may also comprise generating a first phase modulated signal in a first DDFS and generating a second phase modulated signal in a second DDFS, or in a single DDFS with two integrated digital-to-analog converters, and upconverting and combining the first and second phase modulated signals and amplitude modulating the combined upconverted signals in a non-linear device. A processor may be enabled to control the generation of the first and second phase modulated signals.

The invention discloses a digital nonlinear power amplifier which utilizes intelligent closed-loop control. Control signals pass through a digital module and the like and then are output by an output circuit and regulate current values generated by an upper coil and a lower coil of a differential electromagnet. Current feed back values are in two channels, one of the current feed back values is fed back to an output signal converter after real-time detections to perform fast protection for an output driving, and the other one of current feed back values and material parameters are input to a compensating parameter determining module. A position sensor signal feeds back collected signals to the compensating parameter determining module for centralized processing. And then a microprocessor in a system quickly finds compensating parameters in a nonlinear compensation database and overlays the compensating parameters to amplification signals to achieve nonlinear compensation amplification. The nonlinear power amplifier provides technical basis for the practical application of active magnetic levitation and a system controller can be a standard part. The nonlinear power amplifier can play a key role in the achievement of free debugging and mass industrial popularization and application of an active magnetic levitation system.

In one embodiment, a non-linear power amplifier generates an amplified output signal based on a pre-distorted signal generated by a digital pre-distorter based on an input signal. A feedback path generates a feedback waveform based on the amplified output signal. The feedback waveform is aligned in time with the input signal at the waveform level to identify a corresponding reference waveform. The feedback waveform and the corresponding reference waveform are both divided into a plurality of sub-waveforms. Each feedback sub-waveform is independently aligned in phase with its corresponding reference sub-waveform. The resulting plurality of phase-aligned feedback sub-waveforms are then combined to form a hybrid-aligned waveform that is compared to the reference waveform to adaptively update the digital pre-distorter.

A system and method to optimize the efficiency of an amplifier device is provided by the including a non-linear amplifier in a mobile radio device. A phase displaced signal in relation to the input signal is respectively produced in the amplifier device with a non-linear power amplifier and in a plurality of push-pull successive phase modifiers, and the outputs of the phase modifier are connected by a passive component.