Device and method for compensating for nonlinearity of power amplifier with predistortion in IF band

A power amplification system for receiving and amplifying a RF input signal, comprising:

• a first downconverter for receiving the RF input signal and converting the frequency band of the RF input signal into an IF band to output an IF input signal;
• a predistortion unit for receiving the IF input signal, predistorting the IF input signal to compensate for the nonlinearity, and outputting an IF predistorted signal;
• an upconverter for converting the frequency band of the IF predistorted signal into a RF band to output a RF predistorted signal;
• an amplifier for receiving and amplifying the RF predistorted signal to output an RF output signal;
• a coupler connected to an output terminal of the amplifier;
• and
• a second downconverter for receiving the RF output signal through said coupler and converting the frequency band of the RF output signal into the IF band to provide an IF output signal to said predistortion unit,
• wherein said predistortion unit determines a predistortion level based on the IF input signal and the IF output signal.

In a power amplification system including an amplifier for amplifying a RF input signal to a RF output signal, a method of compensating for nonlinearity of the amplifier comprising the steps of:

• (a) downconverting the frequency band of the RF input signal into an IF band to provide an IF input signal;
• (b) predistorting the downconverted IF input signal to compensating for the nonlinearity of the amplifier;
• and
• (c) upconverting the predistorted IF signal into an RF band and providing the upconverted signal to the amplifier so that the amplifier amplifies the upconverted signal to the RF output signal,
• wherein the RF output signal of the amplifier is received and converted into an IF band to provide an IF output signal, and a predistortion level is determined based on the IF input signal and the IF output signal.