A Dual-Input-Assisted Second-Harmonic Precancellation Technique for Ultrawideband Power Amplifiers

This letter presents a new in-band harmonic suppression (HS) transmitter architecture using a dual-input-assisted harmonic precancellation technique. The proposed scheme is divided into three paths: the direct path, the error path, and the main path. By controlling the phase difference and amplitude ratio between the direct path and error path, the second HS of the main power amplifier (PA) can be achieved. The proposed scheme avoids high sampling rates, complex signal processing, and harmonic modeling by obtaining harmonic nonlinearity in advance. In addition, it has the advantages of being wideband, low cost, and less bulky compared with the conventional scheme. The proposed scheme is demonstrated to transmit a 10-MHz LTE signal from 800 to 3100 MHz. Experimental verification shows that the architecture suppresses the in-band second harmonic by 19–23 dB.