Best Linear Approximation: Revisited

Up till now, the best linear approximation (BLA) has always been determined in the frequency band where a device-under-test (DUT) operates. For the development of complete high-level design models, however, it is mandatory to know the BLA outside this frequency band. In this paper a measurement technique is proposed to extract the in-band as well as the out-of-band BLA of a nonlinear microwave amplifier. The proposed measurement technique is based on a classical vectorial network analyzer measurement combined with a broadband multisine excitation of the DUT.