New envelope currents method to evaluate distortion of communication signals in mixers

This paper reports the extension of the novel envelope current-based approach, NEC, to efficiently analyze mixers excited by communications signals. Compared with classical HB technique, the method presents reduced simulation times and an inexpensive use of computer resources, even in the case of digitally modulated signals. For validation purposes a HEMT mixer has been constructed and characterized with single and two-tone 2-GHz input RF signals, and also output spectra under WCDMA-3GPP signal excitations near the 1-dB compression point have been obtained. Relying on its fast convergence properties, simulations have been performed and demonstrate a very good agreement with the experimental results, specifically spectral regrowth. Actually, the method is a trade-off between precision and simulation time.