vlsi,
If I am reading your question correctly, I think this is more of an issue of IC design rather than how to use Multisim (the circuit you describe is likely very complex and would involve many CMOS/transistor components). If you have an existing or partial circuit already ready to start with, the group could better assist with how to implement or use in Multisim for simulation. Although it is possible to model a comlex digital parts with CMOS equivalent logic and gates, most of the more complex digital parts in Multisim are modeled in XSPICE, which allows the behavior to be described by a truth table and timing descriptions and the pins are modeled in SPICE.
However if you want to use a predefined DFT algorithm inline within a circuit simulation, you can likely use with a custom LabVIEW VI, we have several Fourier Transfer algorithms in which you could process a signal coming from a circuit simulation in which the transform and simulation could be run together.
There is an example of how this can be done with an FFT (which is a type of DFT)
https://forums.ni.com/t5/NI-Circuit-Design-Community/Simple-Multisim-API-Continuous-Waveform-Process...
Another idea is to use our co-simulation technology in Multisim v12 together with the LabVIEW Control Design tools. The LabVIEW Control Design package has several discrete signal processing algorithms built in and you could use them together for very precise mixed signal co-simulation between an electrical simulation and a discrete processing algorithm.
Regards,
Pat N
