3.11 CONCLUSION

This chapter has traced new perspectives on the use of Volterra series analysis for the modeling of nonlinear band-pass applications in modern RF and microwave communication systems. A simple and elegant Volterra operator acting directly onto the complex-envelope signals has been derived using the signal conjugate duality . This applies to both the original Volterra series framework and the so-called modified Volterra series expansion. It is shown that the modified Volterra series framework allows first-order and quasi-second-order truncation that provides good modeling accuracy from mildly to highly nonlinear operation in wideband applications. The models are shown to be applicable to the main functional operations found in RF and microwave transmitters (amplification, mixing, frequency conversion, (de)modulation, biasing, and so forth). The two model structures derived from these truncations, called first-order modified Volterra model (FMVM) and nonlinear complex-envelope impulse response model (NCIR) model are single integral forms that can be efficiently implemented through canonical nonlinear filter structures.