Predicting the power rating of a multi-channel linear amplifier

The demand for much greater flexibility in the frequency planning of radio networks has led to the development of a new base station transmitter architecture. A single highly linear multi-channel amplifier could replace the conventional high-level combination of individual amplifiers using selective cavities. This new architecture allows much greater flexibility in frequency planning than a cavity combiner, together with an increase in power efficiency over that of a hybrid combiner. However, the power rating of this single amplifier, which carries a complex signal consisting of the sum of all the individual modulated carriers, must be carefully considered. For example, the peak envelope power of a transmitter carrying sixteen channels at 10 Watts each could be as high as 2.56 kW. The work presented in this paper complements an earlier analysis into the statistical behaviour of the envelope of a multi-carrier signal, by investigating the degree of distortion introduced by limiting the multi-carrier envelope, with a view to reducing the peak envelope power.