Crosspoint switch array crosstalk in the intraoperative evoked potential monitoring amplifier

In biomedical electrical equipment for evoked potentials recording, large crosspoint switch array is used for connecting recording electrodes to different amplifier inputs. As today electrode count can exceed 64, while the amplifier count can be 16, size of crosspoint switch array could be at least 64/spl times/32. Such a large crosspoint switch cannot be made sufficiently small and cheap by using electromechanical switches. By simultaneously using several standard large CMOS crosspoint switch arrays (with size of 16/spl times/16), small size and substantially lower price of the crosspoint switch array can be achieved. One of the main questions in using CMOS crosspoint switch arrays is how much of crosstalk they introduce among channels. Analysis presented in this paper will reveal which elements in the crosspoint switch array contribute to the crosstalk. At the end measured data and data numerically calculated using proposed electrical models is compared.