Abstract: A linearizer for a non-linear transmitter includes a tap delay line that provides samples of an input signal at selected times. At least one Volterra tap is coupled to the tape delay line. The Volterra tap includes a lookup table representation of a polynomial. An adaptive controller is coupled to the Volterra tap for modifying values in the lookup table.

Abstract: A linearizer for a non-linear transmitter and method include a gain regulator and predistorter adapted to be coupled to a non-linear transmitter in various configurations. Bounding controllers are coupled to the gain regulator and predistorter to maintain normal operation of a transmit path to prevent unstable transmitter operation.

Abstract: A linearizer for a non-linear transmitter includes a tap delay line that provides samples of an input signal at selected times. At least one Volterra tap is coupled to the tape delay line. The Volterra tap includes a lookup table representation of a polynomial. An adaptive controller is coupled to the Volterra tap for modifying values in the lookup table.

Abstract: A linearizer for a non-linear transmitter includes a tap delay line that provides samples of an input signal at selected times. At least one Volterra tap is coupled to the tape delay line. The Volterra tap includes a lookup table representation of a polynomial. An adaptive controller is coupled to the Volterra tap for modifying values in the lookup table.

Abstract: A linearizer for a non-linear transmitter includes a tap delay line that provides samples of an input signal at selected times. At least one Volterra tap is coupled to the tape delay line. The Volterra tap includes a lookup table representation of a polynomial. An adaptive controller is coupled to the Volterra tap for modifying values in the lookup table.

Abstract: A power amplifier system includes a nonlinear power amplifier that receives a predistorted input signal. A receiver receives an output signal from the power amplifier and provides an observed signal. A bias controller provides a delayed dynamic bias signal to the power amplifier wherein the bias signal delay is dynamic and is a function of the observed signal for synchronizing the predistorted input signal with the dynamic bias signal. A method is also described that alternately adjusts predistortion delays and bias signal delays as a function of observed signals.

Abstract: An adaptive controller for linearization of transmitters using predistortion of the input signal has reduced sensitivity to impairments such as gain variation, phase noise or modulation/demodulation frequency instability by linearizing an adaptively normalized gain provided through a separate estimation and cancellation of linear gain variations. Values of a nonlinear and a linear gain blocks, cascaded with the linearized transmitter and called respectively a predistortion block and a gain regulation block, are independently adjusted by two different adaptive controllers. In one embodiment, four banks of real gain elements compose the predistortion block and realize an arbitrary step-wise approximation of a generalized 2×2 transmit gain matrix of nonlinear functions. In a further embodiment cancellation of a DC level bias multi-channel impairment is provided by an adaptively adjusted signal adder inserted in the transmit chain between the predistortion block and the linearized transmitter.

Abstract: An adaptive controller for linearization of transmitters using predistortion of the input signal has reduced sensitivity to impairments such as gain variation, phase noise or modulation/demodulation frequency instability by linearizing an adaptively normalized gain provided through a separate estimation and cancellation of linear gain variations. Values of a nonlinear and a linear gain blocks, cascaded with the linearized transmitter and called respectively a predistortion block and a gain regulation block, are independently adjusted by two different adaptive controllers. In one embodiment, four banks of real gain elements compose the predistortion block and realize an arbitrary step-wise approximation of a generalized 2×2 transmit gain matrix of nonlinear functions. In a further embodiment cancellation of a DC level bias multi-channel impairment is provided by an adaptively adjusted signal adder inserted in the transmit chain between the predistortion block and the linearized transmitter.

Abstract: A bank of complex gain elements is used to provide a step-wise approximation of an arbitrary complex-gain predistortion function for a nonlinear transmitter. The bank of gain elements is in an adaptive loop realizing adaptive control. The adaptive loop is closed between an Input of the gain bank and an output of the transmitter through a linear receiver at an adaptive controller composed of a bank of proportional-integral (PI) controllers. The real and imaginary parts of each predistortion gain element are controlled by a corresponding adaptive PI controller. The signals processed by the adaptive controller are represented in orthogonal coordinates in terms of real and imaginary number pairs of complex numbers. The adaptive controller achieves unconditionally stable operation independently from the arbitrary phase rotation in the input signal or the adaptive loop.

Abstract: A communication system uses a reflected signal to determine the location of an impedance mismatch along a transmission path. The system provides a forward signal through the transmission path, and obtains, using a feedback loop, forward signal samples and reflected signal samples from the forward signal and a reflected signal, respectively. Assuming a significant mismatch exists, the system identifies a time delay of any impedance mismatch from the forward signal samples and the reflected signal samples. The physical location of the mismatch along the transmission path is determined based on the time delay and a propagation velocity of the forward signal through the transmission path. The magnitude of the mismatch is determined based on a voltage gain calculation, a loss profile of the transmission path, the propagation velocity, and the time delay. In one embodiment, the method is carried out in a communications base station that includes an amplifier, a feedback loop, a feedback receiver, and a processor.

Abstract: A bank of complex gain elements is used to provide a step-wise approximation of an arbitrary complex-gain predistortion function for a nonlinear transmitter. The bank of gain elements is in an adaptive loop realizing adaptive control. The adaptive loop is closed between an Input of the gain bank and an output of the transmitter through a linear receiver at an adaptive controller composed of a bank of proportional-integral (PI) controllers. The real and imaginary parts of each predistortion gain element are controlled by a corresponding adaptive PI controller. The signals processed by the adaptive controller are represented in orthogonal coordinates in terms of real and imaginary number pairs of complex numbers. The adaptive controller achieves unconditionally stable operation independently from the arbitrary phase rotation in the input signal or the adaptive loop.

Abstract: An adaptive controller for linearization of transmitters using predistortion of the input signal has reduced sensitivity to impairments such as gain variation, phase noise or modulation/demodulation frequency instability by linearizing an adaptively normalized gain provided through a separate estimation and cancellation of linear gain variations. Values of a nonlinear and a linear gain blocks, cascaded with the linearized transmitter and called respectively a predistortion block and a gain regulation block, are independently adjusted by two different adaptive controllers. In one embodiment, four banks of real gain elements compose the predistortion block and realize an arbitrary step-wise approximation of a generalized 2×2 transmit gain matrix of nonlinear functions. In a further embodiment cancellation of a DC level bias multi-channel impairment is provided by an adaptively adjusted signal adder inserted in the transmit chain between the predistortion block and the linearized transmitter.

Abstract: A significant part of the cost of a base station in the cellular mobile radio system is the power amplifier. Thus it is desirable to maximise usage of a power amplifier and in particular to gain the best power output from the amplifier or to improve its efficiency. Such power amplifiers, however, must operate within strict spectral boundaries and thus power amplifiers are typically over-specified in order to ensure that the spectral requirements are met. By measuring the output of the amplifier and determining distortion factors and then adaptively adjusting the operating characteristics of the amplifier, the degree of over-specification of the amplifier required may be reduced with consequent cost and environmental savings.

Abstract: A significant part of the cost of a base station in the cellular mobile radio system is the power amplifier. Thus it is desirable to maximise usage of a power amplifier and in particular to gain the best power output from the amplifier or to improve its efficiency. Such power amplifiers, however, must operate within strict spectral boundaries and thus power amplifiers are typically over-specified in order to ensure that the spectral requirements are met. By measuring the output of the amplifier and determining distortion factors and then adaptively adjusting the operating characteristics of the amplifier, the degree of over-specification of the amplifier required may be reduced with consequent cost and environmental savings.

Abstract: A high power amplifier (103, FIG. 7) comprises a basic power module (15, FIG. 7), a parameter generator (50, FIG. 7), an amplifier gain model (60, FIG. 7), and a predistortion module (40, FIG. 7). The high power amplifier amplifies a linear radio frequency signal with a minimum of distortion, even near its maximum power output, by using an adaptive predistortion algorithm comprising an amplifier gain model 60 based upon a polynomial function of the power module 15 gain function and a time constant. The input signal into the amplifier 103 is continually compared with the amplifier 103 output using a Kalman filter, and model parameters are generated to model 60, which generates distortion compensating values that are combined with the input signal in predistortion module 40 to produce a predistorted input signal into power module 15, which generates the amplifier output. Also described are a method (70, FIG. 8) of operating the power amplifier and a base station (101, FIG.