Digital Predistorter for Power Amplifiers

Toshiba has successfully developed a digital predistorter (DPD) that improves the efficiency of a power amplifier in order to reduce the power consumption of a wireless system.

The power amplifier accounts for most of the power consumption of a wireless system. However, it has been difficult to directly reduce the power consumption of power amplifiers because the output signal is distorted by nonlinear behavior. This results not only in a conspicuous degradation of the communication quality of the system itself, but also increased leakage to the adjacent channels, which interferes with other telecommunication systems.

The principle of operation of the DPD is as follows. The distortion of the power amplifier operated with the power consumption decreased in a nonlinear region is measured, then distortion opposite to that of the amplifier is applied to the transmission signal from the signal source. This procedure is performed using highly accurate digital signal processing. When the processed signal is passed through the power amplifier, a high-quality transmission signal without distortion is obtained.

We have succeeded in attaining a 30% reduction in power consumption of a power amplifier compared with the distortion compensation technique using a conventional analog circuit.

DPD for radio-frequency power amplifiers