Abstract: A signal processing device, used to suppress cross-talk nonlinear distortion of a RF front end circuit. The first circuit generates a first PD signal and a second PD signal according to a first input signal and a second input signal. The first PD signal and the second PD signal are provided to a first PA and a second PA of the RF front end circuit. The second circuit generates a first control signal and a second control signal according to a first output signal, a second output signal, a first DPD signal and a second DPD signal, so as to control the first circuit to generate the first PD signal and the second PD signal. The first PA generates the first output signal through a first filter having a first operating BW. The second PA generates the second output signal through a second filter having a second operating BW.