Analog Devices,inc.

Analaog Devices, Inc.

Ganesh Ananthaswamy

Sudheesh A Somanathan

A pre-distortion circuit that may introduce a pre-distortion signal in a communication channel by determining a harmonic signal of the signal to be output. One or more image correction signals of the signal to be output may be determined. The one or more image correction signals may be complex conjugate signal variations of the signal to be output. The harmonic signal, the one or more image correction signals and the signal to be output may be combined into a combined output signal. The combined output signal may be transmitted to a digital-to-analog converter. The predistortion circuit may be implemented in a FPGA, an ASIC, a digital-to-analog converter, and/or a separate IC package.

Digital pre-distortion

Compensating for wideband quadrature imbalance error by introducing inverse complex inputs to phase quadrature estimator filters to generate estimated quadrature distortion; summing estimator quadrature distortion with a delayed version of the actual complex input to obtain estimated quadrature output; comparing the output with the true output to obtain residual quadrature imbalance error; applying a least mean square to the inverse input and imbalance residual error to obtain an updated estimate of filter coefficients; updating the filter coefficients of the phase quadrature estimator; and updating the filter coefficients of a phase quadrature compensator with the filter coefficients of the phase quadrature estimator to obtain a quadrature output pre-compensated for quadrature imbalance error.

Wideband quadrature imbalance compensation system and method

A sample rate conversion is accomplished by presenting to a numerically controlled oscillator (NCO) register a clock input at the desired output rate; first-modifying the NCO register contents responsive to a first factor; determining when the first modified NCO register contents are in a predetermined range and in response to the first modified NCO register contents not being in the predetermined range, presenting the first modified NCO register contents to the input of the NCO register; second-modifying, responsive to a second factor, the first modified NCO register contents when the first modified NCO register contents are within the predetermined range and presenting it to the input of the NCO register; and fetching samples, in response to the first-modified NCO register contents being in the predetermined range and interpolating them to produce a resultant sample value at the output rate, and in response to the contents not being in the predetermined range to interpolate the previous sample to produce a resultant sample value at the output rate.

Sample rate converter system and method

An efficient approach to generating the bias resulting during the joint equalization/decoding of a Complementary-Code-Keying (CCK) based system is provided that includes a bias generator system having a plurality of inputs responsive only to feedback filter coefficients, the bias generator generating, based upon said feedback filter coefficients, a plurality of output signals corresponding to the bias of a Fast Walsh Transform system for cancelling the bias.

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North Andover, MA, United States of America

Ganesh Ananthaswamy