Automatic feed-forward cancellation of modulated harmonic

Abstract

This paper presents an algorithm for the simultaneous linearization and cancellation of modulated harmonics of broadband power amplifiers (PA). The algorithm relies on a joint system identification of the nonlinearity, memory effects and group delay of both the main and harmonic cancellation channels using a recently reported cubic spline basis. The filter-less cancellation of the modulated harmonics uses both the method of predistortion and feedforward while the synchronized PA linearization relies solely on digital predistortion. Experimental verification with a broadband PA yields a reduction of 31 dB of the third harmonic to 59 dBc below the main channel. Simultaneously the linearization provides -40 dB NMSE and 49.5 and 50 dBc ACPR at the fundamental frequency.