106results about "Amplifier with control circuits" patented technology

A remote radio head unit (RRU) system for multiple operating frequency bands, multi-channels, driven by a single or more wide band power amplifiers. More specifically, the present invention enables multiple-bands RRU to use fewer power amplifiers in order to reduce size and cost of the multi-band RRU. The present invention is based on the method of using duplexers and/or interference cancellation system technique to increase the isolation between the transmitter signal and receiver signal of the RRU.

An object of the invention is to provide a polar modulation transmitter that can perform adaptive distortion compensation processing without the need for a synchronization adjustment circuit for synchronizing an input baseband signal and an output signal of a power amplifier. An adaptive operation control section 1501 measures the unbalance amount of an output spectrum of a power amplifier 1 and a coefficient adjustment determination section of the adaptive operation control section 1501 performs iteration control so that if the unbalance amount is equal to or greater than a predetermined threshold value, coefficient information output to a distortion compensation processing circuit 1301 is adjusted and an adjustment is made to distortion compensation processing in the distortion compensation processing circuit 1301 and if the unbalance amount is less than the predetermined threshold value, the coefficient information is maintained, whereby the characteristic change of the power amplifier 1 at the environmental temperature change time can be adaptively compensated for without using a synchronization adjustment circuit for synchronizing an input baseband signal and an output signal from the power amplifier 1.

Apparatus and methods configure digital predistortion linearizers for power amplification of bandlimited signals using non-linear amplifiers. The predistorter is configured to achieve both crest factor reduction (CFR) and predistortion for linearization. One embodiment advantageously reduces processing requirements conventionally associated with CFR by considering only the in-band component, that is, the information bearing component, of the desired signal to be reproduced for those cases in which the mitigation of in-band error vector magnitude (EVM) is preferred over the reduction of spurious out-of-band emissions.

An embodiment of the invention is a predistortion approach to linearize a power amplifier by setting initially the static operation point of the power amplifier in the cut-off region. The architecture is based on the analog-digital combination by a multiplier and digital predistortion control circuit. The predistortion system generates an adaptive output signal to control the RF modulated signal that is the input signal of the power amplifier. The controlled and predistorted signal can contribute to drive a power amplifier with the cut-off static operation point into its amplifying region and simultaneously correct the non-linear distortion when the power amplifier operates to amplify an RF signal.

It is intended to increase the efficiency of a distortion compensation amplification device having a pre-distorter 1. Level detecting means 11 detects a signal level, correspondence storage means 12 outputs a distortion compensation coefficient depending on the signal level, pre-distortion executing means 13 gives distortion with an inverse characteristic to the signal, filtering means 8 outputs a distortion component from a feedback signal output from an amplifier 4, and correspondence acquiring means 14 updates a learning coefficient constituting a function that gives the inverse characteristic so as to reduce the distortion component. The function that gives the inverse characteristic is expressed using a set of orthogonal polynomials. Each orthogonal function is the total sum of products of functions of the input signal and parameters, and the parameter values are set to cause the orthogonal functions to be orthogonal to each other when functions, which are obtained by applying a filter having the same characteristic as that of the filtering means 8 to the functions of the input signal, are replaced for the functions of the input signal constituting the orthogonal functions.

A transmitter (50) includes a low power nonlinear predistorter (58) that inserts predistortion configured to compensate for a memoryless nonlinearity (146) corresponding to gain droop and another memoryless nonlinearity (148) corresponding to a video signal. When efforts are taken to reduce memory effects, such as configuring a network of components (138) that couple to an HPA (114) to avoid resonance frequencies within a video bandwidth (140), high performance linearization at low power results without extending linearization beyond that provided by the memoryless nonlinear predistorter (58). A unadaptable look-up table (370) has address inputs responsive to a magnitude parameter (152) of a communication signal (54), a magnitude derivative parameter (204) of the communication signal (54), and a parameter (346, 366) related either directly or indirectly to battery voltage. The unadaptable look-up table (370) produces a gain-correcting signal (284) that adjusts the gain applied to the communication signal (54) prior to amplification.

A system for processing data streams or signals includes a wave-front multiplexer configured to process first and second input signals into first and second output signals each carrying information associated with the first and second input signals, a first processing unit configured to process a third input signal carrying information associated with the first output signal into a third output signal, a second processing unit configured to process a fourth input signal carrying information associated with the second output signal into a fourth output signal, and a wave-front demultiplexer configured to process fifth and sixth input signals into fifth and sixth output signals each carrying information associated with the fifth and sixth input signals. The fifth input signal carries information associated with the third output signal, and the sixth input signal carries information associated with the fourth output signal.

A method, apparatus, and computer program for modeling mathematically an effect of a plurality of factors on signal distortion caused by a non-linear amplifier are provided. First, there is computed a global model which incorporates a combined effect of the plurality of factors on signal distortion caused by the non-linear amplifier. Before applying the pre-distorted transmission signal to the non-linear amplifier, a transmission signal is pre-distorted with coefficients derived from the global model thus compensating for the signal distortion caused by the non-linear amplifier.

A system for processing data streams or signals includes a wave-front multiplexer configured to process first and second input signals into first and second output signals each carrying information associated with the first and second input signals, a first processing unit configured to process a third input signal carrying information associated with the first output signal into a third output signal, a second processing unit configured to process a fourth input signal carrying information associated with the second output signal into a fourth output signal, and a wave-front demultiplexer configured to process fifth and sixth input signals into fifth and sixth output signals each carrying information associated with the fifth and sixth input signals. The fifth input signal carries information associated with the third output signal, and the sixth input signal carries information associated with the fourth output signal.

Multi-stage crest factor reduction (CFR) techniques are provided for multi-channel multi-standard radio (MSR). A multi-stage crest factor reduction method comprises applying one or more data samples associated with at least one channel of a first technology type to a first individual crest factor reduction block; applying one or more data samples associated with at least one channel of a second technology type to a second individual crest factor reduction block; aggregating outputs of the first and second individual crest factor reduction blocks to generate an aggregated output; and applying the aggregated output to a composite crest factor reduction block. The individual crest factor reduction blocks can be implemented using a sampling rate appropriate for the corresponding technology type. The composite crest factor reduction block operates at a higher sampling rate than the individual crest factor reduction blocks.

An input signal is pre-distorted to reduce distortion 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 is generated by expanding the derivative of a product of a pre-distortion function and the input signal and then relaxing constraints on the pre-distortion function and/or on frequency-dependent filtering associated with the frequency-dependent pre-distortion. In one implementation, four different frequency-dependent pre-distortion signals are generated for the expansion using up to four different pre-distortion functions and up to four different frequency-dependent filters.

The augmented twin nonlinear two-box modeling and predistortion method for power amplifiers and transmitters provides power amplifier distortion modeling and predistortion linearization. A memoryless nonlinearity is combined with a memory polynomial function that includes cross-terms. The method can utilize an augmented forward twin-nonlinear two-box model, an augmented reverse twin-nonlinear two-box model, or alternatively, an augmented parallel twin-nonlinear two-box model. The present two-box models are validated in modeling and predistortion applications. Measurement results demonstrate the superiority of the present two-box models with respect to conventional state of the art models. The present two-box models lead to better accuracy with reduced complexity.

A power amplifier negates a memory effect and is applied a linearizer using a digital predistortion system even in an inexpensive device. The power amplifier compares an input signal power against a sampled component of an output power, and provides predistortion to the input signal power so as to minimize a difference as a result of the comparison. The power amplifier comprises a gain lookup table storing a gain coefficient value corresponding to a temperature address determined for an input power; a phase lookup table storing a phase coefficient value corresponding to the temperature address determined for the input power; a transversal filter, which is input with the input power, and which outputs the temperature address; and a coefficient multiplier modulating the input signal using a gain coefficient value and a phase coefficient value, which correspond to the temperature address and which are read out from the gain coefficient lookup table and the phase lookup table.

A method of generating parameters for a predistortion circuit in an integrated circuit using a matrix is disclosed. The method comprises storing a first column of a first matrix; generating the remaining columns of the first matrix based upon the first column of the matrix; generating a plurality of rows of a second matrix by performing a first set of calculations; and generating the remaining rows of the second matrix by selectively shifting the first rows of the second matrix.

Recursive digital pre-distortion (DPD) techniques are provided. Digital pre-distortion is performed by applying a signal to a recursive system to generate a state vector; providing the state vector as a feedback value to the recursive non-linear system; and applying the state vector to a second function to generate an output signal, wherein at least one of the recursive system and the second function comprise a non-linear function. The recursive non-linear system can be initialized to a known initial value. The recursive system is defined by a system of non-linear differential equations.

A delay mismatched feed forward power amplifier is disclosed. Loop 1 includes a main amplifier and is used to derive a carrier cancelled sample of the main amplifier output. Loop 2 includes an error amplifier used to amplify the carrier cancelled signal derived from Loop 1 operation in order to cancel distortion products generated due to the nonlinear nature of the main amplifier. Loop 2 also utilizes a very short Loop 2 delay line. A significant efficiency gain is provided due to reduced output power losses associated with the Loop 2 delay line. Lower output losses also results in lower distortion levels produced by the main amplifier. This, in turn, reduces the size and performance requirements placed on the error amplifier. A smaller and more efficient error amplifier is employed resulting in further amplifier system efficiency improvement. The delay mismatch is compensated by a third control loop, a special adaptive control algorithm or a combination thereof.

Systems and methods related to linear load modulated power amplifiers. A power amplifier (PA) system can include an input circuit configured to receive a radio-frequency (RF) signal and split the RF signal into a first portion and a second portion. The PA system can further include a Doherty amplifier circuit including a carrier amplifier coupled to the input circuit to receive the first portion and a peaking amplifier coupled to the input circuit to receive the second portion. The first portion and the second portion can have different phases and/or different powers. The PA system can further include an output circuit coupled to the Doherty amplifier circuit. The output circuit can be configured to combine outputs of the carrier amplifier and the peaking amplifier to yield an amplified RF signal.

Provided is a predistortion apparatus which performs predistortion by reflecting a memory effect when linearizing an output of a nonlinear device using a wideband signal. The predistortion apparatus includes a predistortion unit and a coefficient extraction unit. The predistortion unit selects and outputs one of outputs of the sub-predistorters as an output signal according to intensity of an input signal. The coefficient extraction unit selects one of a plurality of coefficient extractors according to intensity of a nonlinear signal which is generated in response to the output signal, extracts a plurality of predistortion coefficients with the nonlinear signal and the output signal, and delivers the extracted predistortion coefficients to the predistortion unit. Accordingly, the memory effect is reflected even when the input signal is a wideband signal.

An envelope tracking current bias circuit of a power amplifier circuit including a power amplifier includes a first current source circuit configured to generate a first bias current based on a reference voltage, a second current source circuit configured to generate a second bias current based on an envelope voltage of an input signal, and a bias current generator configured to generate a first envelope tracking bias current based on the first bias current and the second bias current, and supply the first envelope tracking bias current to the power amplifier circuit to reduce amplitude modulation-phase modulation (AM-PM) distortion of the power amplifier circuit.