60 results about "Power amplifier linearization" patented technology

A system for linearizing the output of a high power amplifier (HPA) designed to transmit an RF modulated signal includes in its transmit section a digital up-converter for processing baseband input signals and generating a desired digital RF waveform, T(s). The desired digital RF waveform T(s) is then fed to a digital predistorter circuit for producing a predistorted digital RF waveform P(s)T(s) which, as modified, may be applied via a high sampling speed high linearity digital to analog converter to the high power amplifier (HPA) to produce an output signal which is a linear function of the baseband input signal. The digital predistorter circuit may be of the adaptive type or of the predictive type. Circuits embodying the invention may include encoding circuitry for converting multi-bit signals to a serial stream of single-bit pulses for enabling simplification in the digital to analog conversion. In accordance with the invention, corrections for non-linearity of the HPA may be made directly on the RF waveform using ultra-high speed superconducting electronics (SCE) and decreasing the time delay between sensing a transmitted signal and generating a correcting (linearizing) signal.

The invention discloses a power amplifier linearization correcting circuit and method based on multi-channel feedback, relates to a linearization technology in the technical field of communication, and aims to provide a power amplifier linearization correcting circuit and method capable of self-adaptively regulating a predistortion parameter of a system by tracking the linearization characteristic of a radio frequency power amplifier. The power amplifier linearization correcting method is technically characterized in that a signal output by a power amplifier is subjected to frequency spectrumdivision and is coupled to a feedback system by utilizing a plurality of paths of channels; a data recovery circuit recovers a plurality of paths of feedback information to form a path of signal; a predistortion trainer calculates the predistortion parameter by utilizing a baseband signal and a recovered feedback signal; a predistortion trainer A adds a predistortion signal complementing a nonlinear distorted signal of the power amplifier according to the predistortion parameter; and the predistortion signal in the baseband signal is counteracted in the power amplifier, thereby realizing the linearization correction of the power amplifier. The invention is mainly used for nonlinear predistortion correction of a radio frequency signal emission system.

An input signal is pre-distorted to reduce spurious emissions resulting from subsequent signal amplification. Frequency-dependent pre-distortion is preferably implemented in combination with frequency-independent pre-distortion, where the frequency-dependent pre-distortion corresponds to amplifier distortion that has a magnitude that is proportional to the frequency offset from the carrier frequency and a ±90° phase shift on either side of the carrier frequency. The frequency-dependent pre-distortion is generated by differentiating waveforms corresponding to two different sets of pre-distortion parameters with respect to time. In one embodiment, one of the differentiated waveforms is applied to a positive-frequency filter and the other to a negative-frequency filter to generate positive- and negative-frequency pre-distortion signals, respectively, to account for asymmetries in the amplifier characteristics. In another embodiment, only one of the differentiated waveforms is applied to an asymmetric filter (i.e., either a positive-frequency filter or a negative-frequency filter).

A predistorter for the linearization of a power amplifier is provided. The predistorter can incorporate a field effect transistor (FET), which permits a design having low power consumption and broad band characteristics. The predistorter can be appropriate for integration with the power amplifier, unlike the conventional predistorters, because the subject predistorter does not significantly increase the size and complexity of the wireless system. In an embodiment, the subject predistorter can be coupled with a gate bias circuit of a power amplifier. When the predistorter is coupled with the gate bias of a power amplifier, the predistorter can function as linearizer as well as an adaptive gate bias circuit.

Predistortion may be employed to avoid distortion in the output of a power amplifier (PA) in a transmitter, while maintaining transmit power. An active transmission signal, instead of test tones, may be used for training a predistorter for the PA, and for the entire analog transmit path of the transmitter, via a loopback path from the output of the PA to the input of a receiver path. The transmitter may include an upconverter, and the receive path may include a downconverter, which may therefore both be included in the loopback path, helping eliminate phase noise. The predistortion training may incorporate fractional timing correction, to properly align the amplified version of the original TX signal received via the loopback path with the original TX signal. The transfer function of the PA may be estimated as a polynomial function, obtaining the coefficients of the polynomial function using adaptation techniques according to one of a number of possible different methods, e.g. through curve fitting using a least mean square (LMS) algorithm.

The invention relates to the technology of digital pre-distortion, provides a novel digital pre-distortion structure, and achieves a good effect in the linearization of a power amplifier. According to the technical scheme, a memory polynomial digital pre-distortion method based on a piecewise linear function includes: the input of a pre-distortion module is y(n)/G, and the output is the conjugate of z(n), and G is the gain of the power amplifier. An input signal is x(n), the input signal passes through a structure which is the same with the pre-distortion module to generate an output signal z(n), e(n)=z(n)-the conjugate of z(n), e(n) is minimized by employing the recursive least squares algorithm iteration, and the signal is linearly amplified. The method is mainly applied to linearization occasions of the power amplifiers.

A feed forward power amplifier system and method identify active channels across a frequency band to suppress unwanted intermodulation distortion (IMD) products in a communications signal such as a single- or multi-carrier communications signal. A scanning receiver identifies at least one active channel in a frequency band, and identifies at least one portion of the frequency band likely to include IMD products based upon the identified active channel(s). Based upon the identified portion of the frequency band, IMD products are suppressed from the communications signal, e.g., by controlling the magnitude and/or phase of a suppression signal mixed with the communications signal.

The invention relates to a kind of linearization method of power amplifier in signal process field, the invention acquires the enveloped spectrum information of nonlinear distorted signal of power amplifier from front feedback signal counteraction loop, and feedbacks then to the input channel of power amplifier through degenerative feedback loop, and superimposes and modulates the enveloped spectrum, with the input signal, and forms the input signal pre-skewness, realizes the linear amplification of power amplifier. The device includes front feedback signal counteraction model, nonlinear skewness enveloped spectrum degenerative feedback model which is the enveloped spectrum information acquired from the front feedback signal counteraction model, and feedbacks it to the input channel of the power amplifier to be modulated into the enveloped spectrum.

The invention relates to a radio-frequency power amplifier linearization system based on a broadband modulator. The system comprises a receiving device, a channel and an emitting device. The emitting device at least comprises a test data generation device, a predistortion device, a modulation device and a power amplification device. The receiving device at least comprises a synchronous demodulation device, a data recovery device and a predistortion parameter calculation device. According to the predistortion parameter calculation device, a predistortion coefficient vector A is acquired by the optimized variable step size LMS algorithm, and the predistortion device is configured through the acquired coefficient. After an emitted signal matrix U passes the predistortion device, the predistortion device output vector Z is acquired by that Z = UA. According to the system, on the basis that the original LMS algorithm is not modified, the segment interval is refined and the step size is replaced, the step size factors of the LMS algorithm are corrected, the predistorted out-of-band rejection is increased by about 3dB and is closer to the optimal coefficient, and the nonlinear predistortion compensation effect is improved.

An exemplary system comprises a linearizer, a power amplifier, and a feedback block. The linearizer may be configured to use a predistortion control signal to add predistortion to a receive signal to generate a predistorted signal. The power amplifier may be configured to amplify power of the predistorted signal to generate a first amplified signal. The power amplifier may also add high side and low side amplifier distortion to the predistorted signal. The high side and low side amplifier distortion may cancel at least a portion of the predistortion. The feedback block may be configured to capture a feedback signal based on a previous amplified signal from the power amplifier, to determine high side and low side distortion of the captured feedback signal, and to generate the predistortion control signal based on the determined high side and low side distortion.

The power amplifier mainly includes a main amplifier, two splitters, one combiner, one subtracter, two phase shifters, one attenuator and one error amplifier. The splitters, subtracter and combiner are designed in the form of 90-degree or quadrature hybrid couplers. A quadrature hybrid can be implemented with any lumped or transmission-line elements and has an important advantage compared to the in-phase splitter that at equal values of reflection coefficients from loads connected to the in phase and 90° phase shift terminals, the reflection wave is lacking at the main input terminal and, consequently, the input voltage standing wave ratio of a quadrature hybrid does not depend on the equal load mismatch level.

The invention discloses a method for realizing memory-type power amplifier linearization and its baseband predistortion device. The method firstly obtains a loop delay and a parameter of the memoryless predistortion unit by a narrow band training sequence with a specific frame structure and a corresponding self-adaptive algorithm, then compensates the memory effect of the power amplifier when transmitting the broad band signals by an equalizer and an equalizing arithmetic. The base band predistortion device comprises a narrow band training sequence generating unit, a self-adaptive memoryless predistorter, a self-adaptive equalizer. The output of the narrow band training sequence generating unit is fed to the memoryless predistortion unit, modifies the parameters of the memoryless predistortion unit by the self-adaptive algorithm, inputs the broad band signal sequence to the self-adaptive equalizer after the algorithm is convergent, modifies the parameter of the equalizer to compensate the memory effect of the power amplifier. The invention has a low computation, which is easy to realize and suitable for correcting the non-linear property of the power amplifier with the memory effect and the common power amplifier.

A RF-digital hybrid mode power amplifier system for achieving high efficiency and high linearity in wideband communication systems is disclosed. The present invention is based on the method of adaptive digital predistortion to linearize a power amplifier in the RF domain. The power amplifier characteristics such as variation of linearity and asymmetric distortion of the amplifier output signal are monitored by the narrowband feedback path and controlled by the adaptation algorithm in a digital module. Therefore, the present invention could compensate the nonlinearities as well as memory effects of the power amplifier systems and also improve performances, in terms of power added efficiency, adjacent channel leakage ratio and peak-to-average power ratio. The present disclosure enables a power amplifier system to be field reconfigurable and support multi-modulation schemes (modulation agnostic), multi-carriers and multi-channels. As a result, the digital hybrid mode power amplifier system is particularly suitable for wireless transmission systems, such as base-stations, repeaters, and indoor signal coverage systems, where baseband I-Q signal information is not readily available.

The invention relates to a wireless communication technology, aims to solve the problem of influence on wireless communication quality since an existing power amplifier linearization technology has a relatively high requirement on branch consistency of a power amplifier and is difficult to implement in engineering practice, and provides a linear transmission method based on a plurality of antennae. The method comprises the following steps that: a transmitting end performs signal decomposition on a broadband modulation signal to be transmitted, decomposes a broadband modulation signal of a non-constant envelope into a plurality of paths of constant envelope signals, performs power amplification on the paths of constant envelope signals respectively, and transmits amplified signals corresponding to transmitting antennae respectively; and a receiving end receives the paths of constant envelope signals through a plurality of paths of receiving antennae respectively, performs power amplification on the paths of constant envelope signals, and performs linear synthesis on the amplified paths of constant envelope signals, wherein the number of the receiving antennae is the same as the number of the transmitting antennae. The method is suitable for a wireless communication system.

The invention discloses a predistorter and TD-SCDMA power amplifier mode of predistorter, which is characterized by the following: reaching broad frequency intermodulation component at non-linear generator, broad output dynamic tracing scale, broad working band and good heat tracing main-power amplifier path; setting two circuits in the predistorter with the first circuit generating non-linear component to cancel the carrier component and the second circuit generating entire predistortion signal with original carrier component and needed non-linear component; obtaining better linear modification with power amplifier; fitting for wireless launcher power amplifier linear equipment domain.

Procedures for decorrelating the branch signals of a signal adjuster of an amplifier linearizer are presented herein. The decorrelation procedures can be performed with or without self-calibration.

A remote radio head unit (RRU) system for achieving high efficiency and high linearity in wideband communication systems is disclosed. The present invention is based on the method of adaptive digital predistortion to linearize a power amplifier inside the RRU. The power amplifier characteristics such as variation of linearity and asymmetric distortion of the amplifier output signal are monitored by a wideband feedback path and controlled by the adaptation algorithm in a digital module. Therefore, embodiments of the present invention can compensate for the nonlinearities as well as memory effects of the power amplifier systems and also improve performance, in terms of power added efficiency, adjacent channel leakage ratio and peak-to-average power ratio.; The present disclosure enables a power amplifier system to be field reconfigurable and support multi-modulation schemes (modulation agnostic), multi-carriers, multi-frequency bands and multi-channels. As a result, the remote radio head system is particularly suitable for wireless transmission systems, such as base- stations, repeaters, and indoor signal coverage systems.