Group delay and phase measurements at converters and multistage converters without LO access

This paper describes a new technique that allows group delay and relative phase measurements of frequency converters and mixers that don´t have access to the local oscillator or the reference signal. In contrast to the methods offered by network analyzers in the past, the measurement accuracy of this technique is independent of the frequency and phase stability of the internal local oscillator of the DUT. The key of this new method is, that the DUT is stimulated with an nearly arbitrary two-tone signal. The phase difference between these two carriers is measured at the input and the output of the DUT to derive the group delay and the relative phase of the conversion loss of the DUT.