DISTORTION CONTROL

摘要

The predistorter control circuitry described herein provides amplitude and/or phase control signals for controlling a predistorter used, for example, to linearise a non-linear RF amplifier. When used with such a non-linear RF amplifier, these predistortion control circuits operate by sampling both the pure input to the non-linear RF amplifier (710) and its distorted output (724). These two sampled signals are then squared using detectors (716, 730) having a squaring function. The square of the signal representing the pure input to the RF amplifier to be linearised is then squared again (722) to obtain a signal having fourth order reference terms and the resulting signal is correlated (746, 752) with the square of the signal representing the distorted output of the amplifier to be linearised in order to generate the amplitude and/or phase control signals. The predistorter control circuits may use main tone cancellation processes (344, 352, Figure 3) and may be adapted to cope with low input frequencies (Figure 4).