| 摘要 |
An apparatus and method for generating an envelope predistorted radio frequency signal which avoids undesirable spurious emissions. A complex baseband signal, having an in-phase component I and a quadrature component Q, is sampled and filtered in a sampling circuit and filter circuit to obtain samples I<SUB>k </SUB>of the in-phase component and samples Q<SUB>k</SUB>, the quadrature component. The magnitude x<SUB>k </SUB>of each sample pair is determined in a first calculation circuit. An amplitude and phase distortion factor D<SUB>k</SUB>, based on scaled values of the archyperbolic tangent and the hyperbolic tangent of the baseband sample magnitude is determined in further calculation circuit and a multiplier. Each sample I<SUB>k </SUB>of the in-phase component and Q<SUB>k </SUB>of the quadrature component is multiplied by the corresponding distortion factor D<SUB>k</SUB>, and the resulting predistorted components combined and upconverted to provide a predistorted baseband signal which is amplified in a power amplifier having hyperbolic tangent distortion.
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