An improved broadband conversion scheme for the large signal network analyzer

The key component of a large signal network analyzer (LSNA) (Van den Broeck and Verspecht, 1994) is the downconvertor, which allows to transform the measured RF spectrum into an IF spectrum by using the harmonic sampling principle. However, a drawback of the harmonic sampling principle is that for broadband signals, a ´descrambling´ of the measured IF spectral components are necessary after downconversion. In this paper the classical 2-port large signal network analyzer is adapted to allow direct conversion of broadband signals. The necessary hardware adaptations are explained and the improved broadband conversion is shown on some significant measurement examples.