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1728results about "Amplifier modifications to reduce non-linear distortion" patented technology

Digital predistortion system and method for high efficiency transmitters

A system for digitally linearizing the nonlinear behaviour of RF high efficiency amplifiers employing baseband predistortion techniques is disclosed. The system provides additive or multiplicative predistortion of the digital quadrature (I/Q) input signal in order to minimize distortion at the output of the amplifier. The predistorter uses a discrete-time polynomial kernel to model the inverse transfer characteristic of the amplifier, providing separate and simultaneous compensation for nonlinear static distortion, linear dynamic distortion and nonlinear dynamic effects including reactive electrical memory effects. Compensation for higher order reactive and thermal memory effects is embedded in the nonlinear dynamic compensation operation of the predistorter in an IIR filter bank. A predistortion controller periodically monitors the output of the amplifier and compares it to the quadrature input signal to compute estimates of the residual output distortion of the amplifier. Output distortion estimates are used to adaptively compute the values of the parameters of the predistorter in response to changes in the amplifier's operating conditions (temperature drifts, changes in modulation input bandwidth, variations in drive level, aging, etc). The predistortion parameter values computed by the predistortion controller are stored in non-volatile memory and used in the polynomial digital predistorter. The digital predistortion system of the invention may provide broadband linearization of highly nonlinear and highly efficient RF amplification circuits including, but not limited to, dynamic load modulation amplifiers.
Owner:TAHOE RES LTD

Wideband enhanced digital injection predistortion system and method

A system for digitally linearizing the nonlinear behaviour of RF high efficiency amplifiers employing baseband predistortion techniques is disclosed. The system provides additive or multiplicative predistortion of the digital quadrature (I/Q) input signal in order to minimize distortion at the output of the amplifier. The predistorter uses a discrete-time polynomial kernel to model the inverse transfer characteristic of the amplifier, providing separate and simultaneous compensation for nonlinear static distortion, linear dynamic distortion and nonlinear dynamic effects including reactive electrical memory effects. Compensation for thermal memory effects also is embedded in the nonlinear dynamic compensation operation of the predistorter and is implemented parametrically using an autoregressive dynamics tracking mechanism. A predistortion controller periodically monitors the output of the amplifier and compares it to the quadrature input signal to compute estimates of the residual output distortion of the amplifier. Output distortion estimates are used to adaptively compute the values of the parameters of the predistorter in response to changes in the amplifier's operating conditions (temperature drifts, changes in modulation input bandwidth, variations in drive level, aging, etc). The predistortion parameter values computed by the predistortion controller are stored in non-volatile memory and used in the polynomial digital predistorter. The digital predistortion system of the invention may provide broadband linearization of highly nonlinear and highly efficient RF amplification circuits including, but not limited to, dynamic load modulation amplifiers.
Owner:INTEL CORP

Power amplifier sharing in a wireless communication system with amplifier pre-distortion

The technique of amplifier sharing is implemented in a system designed to accommodate transmit diversity. In one embodiment of the invention, the amplifiers are shared 1) to amplify a first and a second diversity-encoded signal, each of which represents the information a first signal that is to be transmitted using transmit diversity, and 2) to amplify a second signal to be transmitted without using transmit diversity. The first and second diversity-encoded signals are used to form a first and a second composite signal. Each composite signal is amplified in a different one of two power amplifiers. Each amplified composite signal is then used to form an amplified first diversity-encoded signal and an amplified second diversity-encoded signal. The first and second composite signals can also be formed using the second signal. Each composite signal is then amplified in a different one of the two power amplifiers and the two amplified composite signals are used to form an amplified second signal. In another embodiment of the invention, the first and second composite signals can be formed in the digital domain. Each composite signal is digitally pre-distorted and then modulated onto a transmission frequency signal, such as an RF signal. Each pre-distorted composite signal is then amplified in the respective amplifier.
Owner:ALCATEL-LUCENT USA INC +1

Calibration device and calibration method of multi-input multi-output (MIMO) terminal

The invention provides a calibration device and a calibration method of a multi-input multi-output (MIMO) terminal. The calibration device comprises a second antenna port, a feedback module, a radio frequency receiving module, a comparison module, a distortion degree determination module and a predistortion treatment module, wherein the feedback module is used for feeding back an output signal of a radio frequency emission module to the second antenna port; the radio frequency receiving module is used for obtaining a digitized feedback signal; the comparison module is used for comparing the feedback signal with an input signal and determining whether a power amplifier works in a nonlinear area or not according to a comparison result; the distortion degree determination module is used for determining the distortion degree of the feedback signal when the power amplifier works in the nonlinear area; and the predistortion treatment module is used for adjusting a predistortion coefficient according to the distortion degree when the power amplifier works in the nonlinear area so as to obtain a calibrated predistortion coefficient. The calibration device can be utilized to calibrate a predistortion coefficient lookup table so as to ensure that the MIMO terminal can carry out predistortion treatment by utilizing the calibrated predistortion coefficient lookup table in a working process so as to improve the linear performance of the power amplifier.
Owner:ST ERICSSON SEMICON BEIJING
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