Power amplifier linearization using cubic spline interpolation

An adaptive RF power amplifier linearization technique is presented. The demodulated amplifier output is compared with the baseband input signal to estimate the amplifier's AM-AM and AM-PM characteristics, using cubic spline interpolation. The input signal is predistorted using these estimated characteristics to compensate for the amplifier's nonlinearity. The proposed technique has nearly 14 dB better suppression of the intermodulation products than the complex gain predistortion technique. The out-of-band power emission is about 12 dB lower in the first two adjacent RF channels than is obtained using the Cartesian coordinate negative feedback technique.

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