Characterization and modeling scheme for harmonics at power amplifier output

With upcoming trends of multiband, broadband and ultrawideband transmitters, there is a need for understanding and representing nonlinear transmitter behavior at system level at frequencies other than transmitter frequency, which might fall within the working range of ultra wideband power amplifier (PA) or other PAs. This paper presents characterization setup, data time-alignment technique and modeling scheme to model second harmonic at the output of PA. The method can easily be extended to higher harmonics. The modeling performance is reported in terms of time domain as well as frequency domain validation. Normalized mean square error is used as quantitative measure of performance.