Identifying the Structure of Nonlinear Perturbations in Mixers using Multisine Signals

The objective of this paper is to identify the position of the nonlinearity, a custom designed multisine signal that can be used to excite the signal path of the mixer. This special random-phase multisine signal with a random harmonic grid contains several carefully selected spectral lines that are left unexcited. These "holes" in the spectrum of the signal act as detectors for the presence and the location of the nonlinearities that deviate from the ideal. First the proposed detection algorithm was tested in a simulation to show that it can work in an ideally controlled environment. Afterwards, measurements are performed on a real mixer excited with a special odd random-phase multisine with a two-port large signal network analyzer (LSNA) and detect the position of the unwanted nonlinearities in the device model.