Microelectronics Technology, Inc.

Miroelectronics Technology Inc.

David B Rutan

Khiem V Cai

Don C Devendorf

Matthew S Gorder

Ahmad Khanifar

Armando C Cova

A Dynamic Digital Pre-Distortion (DDPD) system is disclosed to rapidly correct power amplifier (PA) non-linearity and memory effects. To perform pre-distortion, a DDPD engine predistorts an input signal in order to cancel PA nonlinearities as the signal is amplified by the PA. The DDPD engine is implemented as a composite of one linear filter and N&#x2212;1 high order term linear filters. The bank of linear filters have programmable complex coefficients. To compute the coefficients, samples from the transmit path and a feedback path are captured, and covariance matrices A and B are computed using optimized hardware. After the covariance matrices are computed, Gaussian elimination processing may be employed to compute the coefficients. Mathematical and hardware optimizations may be employed to simplify and reduce the number of multiplication operands and other operations, which can enable the DDPD system to fit within a single chip.

Dynamic digital pre-distortion system

A system and method for stabilizing a coefficient set used by a digital predistortion (DPD) engine to apply pre-distortion to a transmit signal and cancel distortion generated by a distorting element or distorting system when transmitting the transmit signal, including obtaining an initial coefficient set; rotating the initial coefficient set to maintain a phase of fundamental components (w(t), . . . , w(t)) of the initial coefficient set as a constant value; averaging in the time domain the rotated coefficient set to obtain an averaged coefficient set; applying the averaged coefficient set to the DPD engine, the initial coefficient set expressed in a first equation [27]; computing the phase of the fundamental components of the initial coefficient set with a second equation [28]; and computing the rotated coefficient set with a third equation [29].

Digital pre-distortion technique using nonlinear filters

A method and computer program product for operating a linearizer for a circuit, including generating a set of coefficients via a characterizer; predistorting a signal input to the circuit responsive to the coefficients and generating a linearized output in response thereto; filtering the signal through a linear digital filter having linear digital filter taps, each tap other than a first tap being successively delayed by one delay unit; generating powers of the signal; inputting the generated powers of the signal through tapped delay lines, each line having nonlinear digital filter taps, each tap other than a first tap being successively delayed by one delay unit; applying the coefficients to the linear and nonlinear digital filter taps; summing each of the nonlinear digital filter taps corresponding to a certain number of delay units; and adding the sum of each of the delay units to a particular linear digital filter tap.

A system, method and computer program product for stabilizing a coefficient set used by a digital predistortion (DPD) engine to apply pre-distortion to a transmit signal and cancel distortion generated by a distorting element or distorting system when transmitting the transmit signal, including obtaining an initial coefficient set; rotating the initial coefficient set to maintain a phase of fundamental components (w(t), . . . , w(t)) of the initial coefficient set a constant value; averaging the rotated coefficient set to obtain an averaged coefficient set; and applying the averaged coefficient set to the DPD engine.

Digital pre-distortion technique using non-linear filters

A linearizer and method. In a most general embodiment, the inventive linearizer includes a characterizer coupled to an input to and an output from said circuit for generating a set of coefficients and a predistortion engine responsive to said coefficients for predistorting a signal input to said circuit such that said circuit generates a linearized output in response thereto. In a specific application, the circuit is a power amplifier into which a series of pulses are sent during an linearizer initialization mode of operation. In a specific implementation, the characterizer analyzes finite impulse responses of the amplifier in response to the initialization pulses and calculates the coefficients for the feedback compensation filter in response thereto. In the preferred embodiment, the impulse responses are averaged with respect to a threshold to provide combined responses. In the illustrative embodiment, the combined responses are Fast Fourier Transformed, reciprocated and then inverse transformed. The data during normal operation is fed back to the data capture, corrected for distortion in the feedback path from the output of the amplifier, converted to basedband, synchronized and used to provide the coefficients for the predistortion linearization engine. As a result, in the best mode, each of the coefficients used in the predistortion linearization engine can be computed by solving the matrix equation HW=S for W, where W is a vector of the weights, S is a vector of predistortion linearization engine outputs, and H is a matrix of PA return path inputs as taught herein.

Growing community of inventors

Manhattan Beach, CA, United States of America

David B Rutan