US 2003/0118125 A1Published application

Distortion compensation circuit

AssigneeNEC Corporation

InventorYoshiaki Doi

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Abstract

To reduce a time period required for convergence of distortion compensation data without impairing any stability of distortion compensation. An error computation and compensation data updating section repeats a computation in which errors between an input orthogonal baseband transmission signal and a feedback signal obtained by demodulating part of the output from a power amplifier is computed to obtain error data and values obtained by multiplying this error data by step coefficients α(rn) and β(rn) are added to distortion compensation data Kn and θn before updating, thereby computing distortion compensation data Kn+1 and θn+1 after updating. Distortion compensation data for compensation on nonlinear distortion is thus updated. Step coefficients α and β are stored in a step coefficient data memory with respect to each of different input signal amplitude values. Step coefficients α(rn) and β(rn) corresponding to input signal amplitude value rn computed by an amplitude computation section are output from the memory to multipliers.

Claims9

Dependent claims

A distortion compensation circuit for making compensation for a distortion caused in amplification means for amplifying an orthogonal baseband transmission signal, comprising:

an amplitude computation section which computes an amplitude value of the orthogonal baseband signal;
an error computation and compensation data updating section which updates distortion compensation data in such a manner that an error computation is performed to obtain an error between the orthogonal baseband transmission signal and a feedback orthogonal baseband signal obtained by demodulating part of an output from said amplification means, and new distortion compensation data is computed by adding, to distortion compensation data before updating, a value obtained by multiplying the error data obtained as a result of the error computation by a step coefficient;
and
a nonlinear distortion compensation computation section which makes distortion compensation on the orthogonal baseband transmission signal on the basis of the distortion compensation data from said error computation and compensation data updating section,
wherein said error computation and compensation data updating section has step coefficient changing means for changing the step coefficient according to the amplitude value computed by said amplitude computation section.

2 more elements

Dependencies are inferred from the claim text.