Modeling of Power Amplifier Nonlinearities Using Volterra Series

Radio Frequency (RF) power amplifiers (PAs) are one of the most important elements in radio telecommunication facilities, which are used to amplify the power of input signals. At the same time, they gradually become the bottleneck for modern telecommunication systems due to the confliction between the linearity and the efficiency, resulting in their relatively high level energy consumption. Volterra kernels are naturally good representations of intermodulation and harmonic distortions, the main distortions in typical power devices, because of their convolutional structures. Some work has been done to model the distortions by using Volterra series. However, Volterra series expansions are usually truncated severely, due to complexity of computation, so that they do not give accurate representations of the original system. It is intended ultimately to apply a timeinvariant, discrete-time Volterra series method in the modelling of RF power amplifiers to assess distortion levels to eliminate or reduce them. Owing to our limited computational facilities, the experimental PA in this preliminary work is only excited in a moderate frequency range, 100Hz to 1kHz. Copyright c © 2005 IFAC