Signal predistortion in radio transmitter

An apparatus, comprising:

• a predistortion unit comprising an interface to receive a transmission signal to be transmitted and a signal modeling a power supply voltage applied to a power amplifier, the predistortion unit being configured to associate an envelope of the received transmission signal and the signal modeling the power supply voltage with predistortion information comprised in a distortion lookup table, wherein the information in the distortion lookup table is obtained from the transmission signal distortion properties of the power amplifier, the predistortion information remaining substantially fixed over time, and to predistort the received transmission signal according to the associated predistortion information in order to compensate for the distortion caused by the power amplifier, and wherein the predistortion unit is further configured to scale the envelope of the received transmission signal according to at least the received transmit power control commands and amplitude distortion lookup table to adjust the envelope of the transmission signal to a desired operational range of the power amplifier.

A radio transmitter comprising:

• a predistortion unit including an interface to receive a transmission signal to be transmitted and a signal modeling a power supply voltage applied to a power amplifier,
• the predistortion unit being configured to associate an envelope of the received transmission signal and the signal modeling the power supply voltage with predistortion information included in a distortion lookup table, wherein the predistortion information in the distortion lookup table is obtained from the transmission signal distortion properties of the power amplifier, the predistortion information remaining substantially fixed over time, and to predistort the received transmission signal according to the associated predistortion information in order to compensate for the distortion caused by the power amplifier, and wherein the predistortion unit is further configured to scale the envelope of the received transmission signal according to at least the received transmit power control commands and amplitude distortion lookup table to adjust the envelope of the transmission signal to a desired operational range of the power amplifier.