An Improved Broadband Conversion Scheme for the Large-Signal Network Analyzer

The key component of a large-signal network analyzer (LSNA) is the downconvertor, which allows the transformation of 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 ldquodescramblingrdquo of the measured IF spectral components is necessary after downconversion. In this paper, the classical two-port LSNA 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.