263 results about "Linear power amplifier" patented technology

A novel apparatus and method of improving the power efficiency of a digital transmitter for non-constant-amplitude modulation schemes. The power efficiency improvement mechanism of the invention leverages the high efficiency of a switched-mode power supply (SMPS) that supplies the high DC current to the transmitter's power amplifier, while compensating for its limitations using predistortion. The predistortion may be achieved using any suitable technique such as digital signal processing, hardware techniques, etc. A switched mode power supply (i.e. switching regulator) is used to provide a slow form (i.e. reduced bandwidth) of envelope tracking (based on a narrower bandwidth distorted version of the envelope waveform) such that the switching regulator can use a lower switching rate corresponding to the lower bandwidth, thereby obtaining high efficiency in the switching regulator. The resulting AM-AM and AM-PM distortions in the power amplifier are compensated through predistortion of the digital amplitude modulating signal which dictates the envelope at the PA input. Similarly, the phase modulation is also compensated prior to the PA, such that once it undergoes the distortion in the PA, the end result is sufficiently close to the desired phase.

An antenna system installation comprising a tower / support structure, and an antenna structure mounted at the top of said tower / support structure, said antenna structure comprises a plurality of antenna elements, a plurality of power amplifiers, each power amplifier being operatively coupled with one of said antenna elements and mounted closely adjacent to the associated antenna element, such that no appreciable power loss occurs between the power amplifier and the associated antenna element, each said power amplifier comprising a relatively low power, relatively low cost per watt linear power amplifier chip, a first RF to fiber transceiver mounted at the top of said tower / support structure and operatively coupled with said antenna structure, and a second RF to fiber transceiver mounted adjacent a base portion of said tower / support structure and coupled with said first RF transceiver by an optical fiber cable.

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.

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

A power amplifier circuit whose performance is optimized by operating its stages in substantially close to a Class B mode by reducing quiescent current during low driver signal levels. As the driver signal amplitude increases, the operation of the amplifier is configured to dynamically adjust to be in a Class AB mode, thereby increasing the power efficiency of the overall circuit at kiw drive levels. A further enhancement to the power amplifier circuit includes a temperature compensation circuit to adjust the bias of the amplifier so as to stabilize the performance in a wide temperature range.

A modular base station enhancing system includes multiple bi-directional amplifiers that are remotely controlled. Duplexers, corresponding to the bi-directional amplifiers, interface the bi-directional amplifiers with base station antenna elements, enabling simultaneous transmission and reception through the antenna elements. A control circuit, located remotely from the base station and the bi-directional amplifiers, enables control of at least one parameter in each of the bi-directional amplifiers to control transmission and reception characteristics of the antennas elements. The controllable bi-directional amplifiers may include a linear power amplifier to amplify transmitted signals and a low-noise amplifier to amplify received signals. The base station enhancing system is interoperable with different types of antenna elements, and may be implemented as a radio frequency (RF) front-end of the base station or as an RF repeater.

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.

According to an exemplary embodiment, an amplification module includes a power amplifier configured to receive an RF input signal and provide an RF output signal. The amplification module further includes an autobias control circuit configured to receive and convert the RF output signal to a control signal. The control signal can cause the power amplifier to have a quiescent current that increases substantially linearly in response to an increase in the RF output power of the RF output signal. The autobias control circuit can include a peak detector / log converter circuit coupled to a first input of a differential amplifier, where the differential amplifier outputs the control signal. The autobias control circuit can further include a DC reference circuit coupled to a second input of the differential amplifier. The amplification module further includes an analog bias circuit coupling the control voltage to a bias input of said power amplifier.

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.

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.

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 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.

Disclosed are devices and methods for improving power added efficiency and linearity of radio-frequency power amplifiers implemented in flip-chip configurations. In some embodiments, a harmonic termination circuit can be provided so as to be separate from an output matching network configured to provide impedance matching at a fundamental frequency. The harmonic termination circuit can be configured to terminate at a phase corresponding to a harmonic frequency of the power amplifier output. Such a configuration of separate fundamental matching network and harmonic termination circuit allows each to be tuned separately to thereby improve performance parameters such as power added efficiency and linearity.

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 discloses a rotating transformer exciting circuit based on sinusoidal pulse width modulation (SPWM), which comprises a microprocessor, an analog demodulation circuit and a power amplification circuit, wherein the microprocessor adopts DSP to perform digital modulation so as to load a required sinusoidal fundamental wave signal to a high-frequency square wave carrier signal to form an SPWM wave signal, and output SPWM waves to the analog demodulation circuit in a differential mode. The analog demodulation circuit adopts a two-circuit duplicate-supply operational amplifier TL082, and one path of the operational amplifier forms a differential proportion calculator, while the other path forms a filter. The power amplification circuit adopts a two-circuit duplicate-supply linear power amplifier PA60 and a resistor to form a two-circuit reversed phase proportioner, and blocks the input sinusoidal fundamental wave signal and amplifies the power to generate an exciting signal and simultaneously drive a two-circuit rotating transformer to work. The rotating transformer exciting circuit has the advantages of simple circuit, safety and reliability, small temperature drift and direct current component, good stability of output signals, and low degree of distortion of output waveforms.

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 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.

A predistortion linear power amplifier utilizes several predistortion computation engines to receive a first carrier signal. The predistortion computation engines also receive input from a predistortion algorithm engine. The predistortion algorithm engine receives its data from a predistortion amplifier sensor that monitors the operating characteristics of the amplifier and also from a feedback control circuit that provides frequency correlated input and feedback data. The processed data from the predistortion algorithm engine is then input into the predistortion computation engine along with the carrier signal. An output combiner circuit takes the output of each predistortion computation engine and generates a single correction estimate, which is then input into the nonlinear amplifier for producing a substantially linear output signal.