The peak limiting of a baseband code-division multiplexed signal applied to a predistorted power amplifier

A multiplexed signal in code division, as well as in frequency division, shows a linear increase of its peak to average power ratio (PAPR) as the number of multiplexed signal increases. When such a high PAPR signal is applied to a power amplifier, out-of-band radiation increases or power efficiency drops. In order to solve these problems, there is a predistorter, which compensates the amplifier's nonlinearity. This method requires the signal that does not exceed the compensation level. We investigate by computer simulation the effect of the peak limiting of a CDM signal at base band when applied to an adaptive predistorted power amplifier. The peak limitation for an adaptive predistorter keeps out-of-band radiation below 80 dB for increased average power levels. Simultaneously, high power efficiency is obtained.