71 results about "Nonlinear power amplifier" patented technology

A predistorter (26) comprises an array (44) of band pass filters (46 to 52) which divide an input signal into components. Each of the components is manipulated using coefficients retrieved from respective look-up tables (54 to 60). The amplitude of each component is used to retrieve a coefficient from its respective look-up table. The amplitude of each component is then multiplied with its respective retrieved coefficient to generate a predistorted amplitude for that component. The predistorted amplitudes are summed (at 80) to produce a predistorted input signal. The predistortion of the input signal is arranged to counter the distortion characteristic of a signal handling element (such as non-linear power amplifier 22 in FIG. 1) to which the predistorted input signal is subsequently supplied. The coefficients in the look-up tables (54 to 60) can be adapted using feed back from the output of the signal handling means (FIG. 5). Fast Fourier transformation and inverse fast Fourier transformation can be used in place of band pass filter array (44) and combiner (80), respectively (FIG. 4).

A phase-amplitude modulator for mobile communications employs a phase lock loop as an input to a nonlinear power amplifier providing phase information with amplitude information used to modulate the power amplifier output to synthesize phase-amplitude for the RF transmission signal.

A polar loop transmitter includes separate phase and envelope paths providing a linearising scheme for an efficient non-linear power amplifier. Loop filters are included in each of the phase and envelope paths to enable the path characteristics to be matched to one another. A polar loop transmitter and other types of envelope elimination and restoration transmitters control the output envelope of the power amplifier by connecting the output of the envelope detector, or in an envelope feedback transmitter, the envelope error signal, to the bias control input of the power amplifier. The transmitter can further include compensation means for compensating for non-linearities in the envelope control means and a loss of feedback control detector to ensure that the feedback signal remains within acceptable limits.

An apparatus linearizing and technique for linearizing a nonlinear power amplifier used in transmitters of systems for digital wireless communications. Linearization of the nonlinear amplifier is achieved by adding additional signals generated from a specification-given input data stream to the output of the nonlinear power amplifier. The invention allows use of nonlinear power amplifier, which typically enjoys a lower current consumption than that of a linear power amplifier, thus increasing the time between batteries recharges (for user transmitter equipment) and / or reducing the overall size, electric bill expenses, and cooling requirements (for network transmitter equipment). Input data, generated by a given digital wireless standard, is raised to a mathematical power by a required number and converted to RF of a transmitted signal frequency. Then all obtained RF waveforms are added with the same amplitude and the opposite phase to the spectrum of sidelobes generated by nonlinearity of a power amplifier.

According to the present invention, a digital pre-distortion device and method for use in a dynamic spectrum allocation system, which uses a breadband frequency range, such as a cognitive radio (CR) system, are implemented. Also, while as conventional pre-distortion device only enable the linearization of a signal of a fundamental frequency band, the digital pre-distortion device and method according to the present invention enable not only the linearization of a basic signal on frequency fc, but also simultaneously enable the elimination of harmonic signals on the high frequencies of 2fc, 3fc, 4fc, etc. The digital pre-distortion device for a broadband power amplifier according to a preferred embodiment of the present invention comprises: a nonlinear power amplifier; an equivalent amplifier model estimator; N pre-distorters; and a coefficient extractor for extracting the coefficients of the N pre-distorters.

A signal and information transmission system for communications or radar and a method of achieving distortionless transmission of linear phase shift keying signals amplified by nonlinear power amplifiers or distorted by up-converters and RF circuits or the channel. Error correcting codes are used to jointly overcome both the distortion by the power amplifiers or up-converters and RF circuits or the channel and the noise. The modulator generates properly pulse shaped PSK signal, which does not have constant envelope. The signal-to-distortion power ratio is maximized to be above 20 dB at the fully saturated power amplifier output. The simplest linear receiver is provided to demodulate the received signal in the presence of radio distortion, channel distortion and noise. The decoder makes decision in the presence of radio distortion, channel distortion and noise. The method guarantees distortionless transmission of PSK signals for communications systems or radar employing power amplifiers of high DC-to-AC power conversion efficiency including class-F, class-E, class-D, class-C, or any of class-A, class-B, class-AB working in the saturation region. The method can achieve high bandwidth efficiency.

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.

The invention discloses a nonlinear system, in particular a device and a method for identifying inverse characteristic of a nonlinear power amplifier, a predistorter of the power amplifier and power amplification equipment using the device for identifying the inverse characteristic of the nonlinear system and the predistorter. The method for identifying the inverse characteristic of the nonlinear system according to an original input signal x(n) and a corresponding feedback output signal y<G>(n) of the nonlinear system comprises the following steps: according to an inverse filter signal x<F> (n) and the feedback output signal y<G>(n), calculating an inquiry form function Q[.]; according to the feedback output signal y<G>(n) and the inquiry form function Q[.], generating a middle predistortion signal z(n); according to the middle predistortion signal z(n) and the original input signal x(n), constructing a filter function F[.]; carrying out inverse filtering on the original input signal x(n) by using parameters of the filter function F[.] to generate an inverse filter signal x<F>(n); repeating each step through iteration till meeting the set condition, wherein the inquiry form function Q[.] and the filter function F[.] represent the inverse characteristic of the nonlinear system.

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.

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.

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 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.

The nonlinearity of power amplifiers (PAs) has been a severe constraint in performance of modern wireless transceivers. This problem is even more challenging for the fifth generation (5G) cellular system since 5G signals have extremely high peak to average power ratio. Nonlinear equalizers that exploit both deep neural networks (DNNs) and Volterra series models are provided to mitigate PA nonlinear distortions. The DNN equalizer architecture consists of multiple convolutional layers. The input features are designed according to the Volterra series model of nonlinear PAs. This enables the DNN equalizer to effectively mitigate nonlinear PA distortions while avoiding over-fitting under limited training data. The non-linear equalizers demonstrate superior performance over conventional nonlinear equalization approaches.

A transmitter stage working according to the envelope restoration principle includes means for providing an amplitude representation and a phase representation of an amplitude and phase-modulated signal to be transmitted, as well as a phase-locked loop with a feed-forward branch and a feedback branch, as well as amplification control means formed to convert the amplitude representation to an amplification control signal, which may be fed into the amplification control input of a nonlinear power amplifier. In the feed-forward branch, a digital / analog converter is arranged. Furthermore, in the feedback branch, an analog / digital converter is arranged, so that the phase detector of the phase-locked loop is implemented in digital form. By an as large as possible proportion of digital signal processing, an inexpensively implementable and exactly working transmitter stage is obtained.

A power amplifier has a non-linear low power pre-distortion amplifier (112) for transforming a carrier signal (111) to a pre-distorted signal (113) having a carrier component with out-of-phase non-linear distortions, and a non-linear power amplifier (114) having non-linear characteristics similar to a portion of the non-linear low power pre-distortion amplifier for generating from the pre-distorted signal a transmission signal (115) having an amplified carrier component with substantially diminished non-linear distortions.

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.

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.

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.

The present invention provides a linear transmitter which adopts non-linear components. The transmitter comprises a digital signal processing unit, an analog signal processing unit, a signal amplification unit, a synthesis unit, and a feedback unit. The digital signal processing unit is used for pre-processing the input signals of the transmitter; the analog signal processing unit is used for transforming digital baseband signals into analog baseband signals, and directly transmitting the signals to the transmission carrier frequency through quadrature modulation; the signal amplification unit adopts a high-efficiency non-linear power amplifier to amplify the radio frequency signals; the synthesis unit is used for synthesizing and transmitting outwards the two types of signals; the feedback unit is used for coupling and processing the transmission signals so as to acquire the out-of-band power value of the transmission signals; wherein, the digital signal processing unit can complete the separation and pre-distortion processing of the input signals, calculating the gain and phase error of the two branches, controlling the gain and the phase of one branch so that the two branches maintain the consistent amplitude and phase, and thus guaranteeing that the transmitter has high linearity and high efficiency.

The invention provides a method, equipment and a system for joint distribution of bits and power to subcarriers. According to hardware parameters of a non-linear power amplifier and channel noise, the relation among the ratio of signal to interference of each subcarrier, the power of the subcarriers and the total power under a non-linear distortion condition is determined, so that non-linear distortion noise generated by the non-linear power amplifier can be taken into account, and the corresponding bit and the corresponding power are jointly distributed to each subcarrier by means of a preset total power minimum iterative algorithm according to the determined relation among the ratio of signal to interference of each subcarrier, the preset input power, the total bits and the bit error rate under the non-linear distortion condition. Compared with the prior art, the method, equipment and the system for the joint distribution of the bits and the power to the subcarriers enable the non-linear distortion of the non-linear power amplifier to be taken into account, ensure the minimization of the total power, and can better meet requirements for a system bit error rate (BET) at the same time.

A channelized amplification system and method for mitigating non-linear amplification effects and controlling spectral re-growth is disclosed. A system includes an input frequency divider for converting a first signal into a plurality of frequency band signals and a plurality of channelized high-efficiency non-linear power amplifiers coupled to the frequency divider. Each of the plurality of frequency band signals occupies a frequency band that is different from one another. The plurality of channelized high-efficiency non-linear power amplifiers receive and amplify the plurality of frequency band signals and produce a plurality of non-linearly amplified signals. The system further includes a frequency combiner coupled to the plurality of channelized high-efficiency non-linear power amplifiers. The frequency combiner combines the plurality of amplified signals and produce a second signal. The system further includes an output band-pass filter coupled to the frequency combiner. Each of the frequency divider and frequency combiner can be a duplexer or a diplexer when the number of the plurality of frequency band signals is two. The system further includes an input band-pass filter for spectrally shaping a signal and a distributor for distributing a signal to a plurality of amplification modules. Each of the amplification modules includes a corresponding frequency divider, a corresponding plurality of channelized high-efficiency non-linear power amplifiers, a corresponding frequency combiner and a corresponding output band-pass filter. The system further includes a radio frequency up-converter coupled to the input band-pass filter.

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.