Transmission device and signal predistortion method thereof

A signal predistortion method applied to a transmission device, wherein the transmission device comprises a signal processing circuit, a transmission chain and a power amplifier, the power amplifier is configured to amplify a radio-frequency (RF) input signal outputted by the transmission chain to generate a RF output signal, and the signal predistortion method comprises:

• performing, by the signal processing circuit, a first signal processing operation on a baseband signal and an in-band predistortion parameter set to generate an in-band predistortion output;
• generating, by the signal processing circuit, the in-band predistortion parameter set according to a difference between a first reference signal and the baseband signal;
• performing, by the signal processing circuit, a second signal processing operation on the in-band predistortion output to generate an out-of-band predistortion output;
• and
• generating, by the signal processing circuit, a full-band predistortion signal to the transmission chain according to the in-band predistortion output and the out-of-band predistortion output so that the transmission chain generates the RF input signal according to the full-band predistortion signal.