259 results about "Linear power amplifier" patented technology

A transmission signal and a pilot signal are predistorted by a digital predistorter 13 by use of a power-series model, and the predistorted output is converted by a digital-analog converter 14 to an analog signal. The analog signal is up converted by a frequency converter 15 to an RF-band signal, which is transmitted after being power-amplified by a Doherty amplifier 16. The pilot signal is extracted by a pilot signal extractor 17 from the output from the Doherty amplifier, and the extracted pilot signal is down converted by a frequency converter 18 to a baseband signal. The baseband pilot signal is converted by an analog-digital converter 19 to a digital pilot signal. A control part 21 detects an odd-order distortion component from the digital pilot signal, and based on the detected result, controls parameters of the digital predistorter.

This invention is about a novel estimation technique for generating a predistortion function to compensate for the AM-AM and AM-PM non-linear conversion distortions of non-linear power amplifiers or non-linear circuits. Based on the cumulative type of power amplifier output envelope, a non-parametric baseband predistortion function is derived. The non-parametric approach avoids any model mismatch. In addition, the technique does not need to demodulate the input signal. Furthermore, it minimizes the effect of the power amplifier non-linearity and significantly improves the system performance

An RF amplifier comprises a power amplifier and a dual bias circuit. A dual bias circuit comprises a constant current source and a constant voltage source for biasing the power amplifier. The power may include a heterojunction bipolar transistor (HBT) or a bipolar junction transistor (BJT).

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.

A multi-channel and multi-carrier Digital Predistortion writing machine of wideband CDMA base station system includes the feedback signal processing channels and at least one multiplexing signal processing channels of multi-carrier base band, of which, each includes the digital base-band peak-clipping frequency processor, digital predistortion processing module, high-intermediate frequency output module and filter, radio frequency access and high power amplifier. The feedback signal processing channel includes the RF feedback channel and A/D converter. The invention uses the base band peak-clipping technology, digital predistortion technology and high-intermediate digital IF technology, to reduce the high cost by the use of the linear power amplifier, and can effectively enhance the launch performance and efficiency of the base station system. The invention does not use the feedback channel switching technology to achieve saving the cost of RF link.

A combined signal of a digital pilot signal and a digital transmission signal is applied to a digital predistorter (20), wherein it is added with odd-order distortions based on a power series model to generate a predistorted signal, then the predistorted signal is converted by a DA converter (31) to an analog signal, then the analog signal is upconverted by a frequency upconverting part (33) to a send frequency band, and the upconverted signal is output after being amplified by a power amplifier (37). A pilot signal component is extracted from the power amplifier output, then odd-order distortion components of the power series model are extracted by a digital predistorter control part (50) from the pilot signal component, and the odd-order distortions in the digital predistorter (20) are controlled to decrease the levels of the distortion components.

A power amplifier with stacked, serially connected, field effect transistors is described. DC control voltage inputs are fed to the gates of each transistor. Capacitors are coupled to the transistors. The inputs and the capacitors are controlled to minimize generation of non-linearities of each field effect transistor and/or to maximize cancellation of distortions between the field effect transistors of the power amplifier in order to improve linearity of the power amplifier output.

Multi-mode power amplifiers that can support multiple radio technologies and/or multiple frequency bands are described. In one exemplary design, a first linear power amplifier supporting multiple radio technologies may be used to amplify a first RF input signal (e.g., for low band) and provide a first RF output signal. A second linear power amplifier also supporting the multiple radio technologies may be used to amplify a second RF input signal (e.g., for high band) and provide a second RF output signal. Each linear power amplifier may include multiple (e.g., three) chains coupled in parallel. Each chain may be selectable to amplify an RF input signal and provide an RF output signal for a respective range of output power levels. An RF input signal may be a phase modulated signal or a quadrature modulated signal and may be pre-distorted to account for non-linearity of the power amplifier.

A power amplifier stage has a first amplifier subsection and a second amplifier subsection coupled in a parallel configuration. The first amplifier subsection receives a signal to be amplified and the second amplifier subsection receives the signal to be amplified via a first delay line. The amplified output signal of the first amplifier subsection is passed through a second impedance inverter and is combined with the amplified output signal from the second amplifier subsection. In a low power mode, the first amplifier subsection operates as a linear amplifier and the second subsection is biased off. In a high power mode, both the first and second amplifier subsections operate as linear amplifiers. Selecting the impedances of the second delay element and the first amplifier to be equal is essential for high power mode operation and greatly improves the amplifier efficiency in the low power mode.

A method and apparatus for direct-conversion transmission generates a first frequency signal that is non-harmonically related to a transmit frequency signal, divides the first frequency signal to obtain a mixing frequency signal, divides the first frequency signal to obtain an intermediate frequency reference signal, generates the transmit frequency signal by using the mixing frequency signal to downconvert the transmit frequency signal into an intermediate frequency feedback signal, and phase-locks the intermediate frequency feedback signal to the intermediate frequency reference signal. The transmit frequency signal may be phase modulated, and may serve as an input to a saturated-mode power amplifier that can be configured for corresponding amplitude modulation. Alternatively, the un-modulated transmit frequency signal serves as the carrier signal input to a quadrature modulator, which imparts I/Q modulations to it, thereby producing a modulated carrier signal for input to a linear power amplifier.

An enhancement type analog predistortion linear power amplifier, including a signal splitter unit, a first main power amplifier, a predistortion generation unit, a delaying filter, a error power amplifier, a 3dB electric bridge, a control cell and a receiver, the input end of the signal splitter unit is a radio frequency input terminal port, the input end of the first main power amplifier and the first input end of the predistortion generation unit are respectively connected to the output end of the signal splitter unit, the first output end of the first main power amplifier is connected to the input end of the delaying filter, the second output end is connected to the second input end of the predistortion generation unit, the output end of the predistortion generation unit is connected to the input end of the error power amplifier, the control cell controls every device, the output ends of the delaying filter and the error power amplifier are connected to the input end of the 3dB electric bridge, and the output end of the 3dB electric bridge is a radio frequency output terminal port. The enhancement type analog predistortion linear power amplifier provided by the invention has the advantages of improved ACPR, self-adapting function, considerably improved integral efficiency of power amplifier, thereby totally meeting the applied request of engineering.

The invention discloses a linear power amplification circuit based on the simulation of predistortion, comprising a predistortion amplifier, a first temperature-controlled attenuator, a simulate predistorter, a second temperature-controlled attenuator, a push-pull amplifier, and a last stage high-power amplifier which are sequentially connected. The invention also discloses a method to use the circuit: the simulate predistorter circuit which has relatively simple topological structure is added to produce a distortion signal of a predistortion signal balanced power amplifier; a matching circuit and a bias voltage of a power tube of the push-pull amplifier and that of the last stage high-power amplifier are adjusted to make the two power tubes complement in amplitude and phase to achieve the predistortion effect and to enable better linearity of the RF output signal. The invention is simple in circuit structure, high in working efficiency, low in cost and occupies little PCB area, which is extremely suitable for the multi-carrier linear power amplification circuits in the TD-SCDMA stations and the repeaters systems.

A linear power amplifier system using pulse area modulation includes: an envelop/phase decomposer for decomposing an input signal into an envelop signal and a phase signal; a pulse area modulator for modulating the envelop signal such that an area of the modulated envelop signal is proportional to an amplitude of the envelop signal; a control signal generator for converting the modulated envelop signal into a control signal; an automatic gain adjuster for equalizing pulse height of the modulated envelop signal; a mixer for mixing the phase signal with the output of the automatic gain adjustor to produce a RF pulse train; a power amplifier for amplifying the RF pulse train, to generate an amplified RF pulse train; and a band pass filter for restoring the original input signal from the amplified RF pulse train. The output level of the power amplifier is controlled by the control signal.

The invention relates to a reconfigurable radio frequency and microwave power amplifier. The reconfigurable radio frequency and microwave power amplifier comprises an input radio frequency switch, anadjustable input matching network, a power amplifier stage, an adjustable output matching network and an output radio frequency switch which are connected in turn, and an adjustable harmonic impedancecontrol network and a bias and control circuit; and the adjustable input matching network and the adjustable output matching network respectively comprise at least one LC network with a fundamental wave impedance conversion function, wherein the LC network comprises at least one reconfigurable device, and the reconfigurable device is connected with a passive device in the LC network in parallel.According to the reconfigurable radio frequency and microwave power amplifier provided by the invention, the reconfigurable harmonic impedance control network and the fundamental wave impedance matching network are realized through the adjustable input matching network, the adjustable harmonic impedance control network and the adjustable output matching network; and when a power amplifier works indifferent bands of a linear power amplifier mode, a load impedance network can be reconfigured in real time, which satisfies the fundamental wave impedance and harmonic load required by each frequency band.

The invention discloses an ultrasonic TOFD (Time of Flight Diffraction) detection method for weld defects based on a linear frequency modulation technology, relating to an ultrasonic detection method for weld defects. The method solves the problem that in the existing ultrasonic detection for large-thickness welding structures, the signal propagation distance and the resolution ratio are mutually contradicted. The method comprises the following steps that: a digital signal generator produces a wideband (Linear Frequency Modulation) LFM pulse signal, and the wideband LFM pulse signal is amplified through a linear power amplifier so as to have corresponding energy for exciting an ultrasound transmitting probe; the ultrasound transmitting probe after being excited produces forced vibration and radiates ultrasonic waves to a test piece; when a control computer executes an acquisition command, a receiving probe receives a detection signal at a corresponding position, and the receiving of the detection signal is completed by a wideband signal acquisition card; and the computer carries out matched filtering processing on the received signal, so that a pulse compression signal is obtained, and according to the time that each wave reaches, the buried depth of a defect can be calculated according to a formula. The method disclosed by the invention is used for detecting weld defects.

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.