Quick general summary: In analog time division multiplexing, after combining several continuous signals into a single line, do you generally need to use some form of sample and hold to reconstruct the continuous signals on the demux output side? Or do mux IC's do this automatically?
My specific application: I'm collecting 256 voltage signals from tiny wires embedded in brain tissue, eventually collecting them on a DAQ card and doing online analysis. The multiplexer (perhaps ADG1606 on both mux and demux side) is intended to reduce the wire-count in the long, expensive cable bundle that connects the on-head signal buffers to the rest of the amplification and digitizing hardware (please see figure - I hope the size is appropriate). From the answers I've gotten so far, I drew what seems to be the necessary general idea, and I'm wondering about specifications and unforseen limitations.
For the sample-and-hold, I'm considering this setup, except that the droop rate (2mV/ms) and sample time (3ms) seem bad for my application. Maxim seems to offer inexpensive SH packages with better specs (DS1843 DS), would you recommend using those instead of making SH stages from opamps and switches as the tutorial outlines?
Am I right in imagining that independent SH circuits synced with the mux timing will reconstruct the original independent pre-multiplexed signal (at least the lower-frequency parts that I care about - 0.1Hz to 9kHz)? Or does the SH switching introduce periods of corrupt output data?
May I skip my late 5000x amplification step (256 channels) by 5000x amplifying the 8 mux lines just before demux? This would save me some space and money.
And, do I need to lowpass filter the brain signal BEFORE it gets to the mux? I have not done this in my current setup (which doesn't have any mux), but with mux I think I may need to worry about aliasing?
You may be able to tell that I'm new to this, so clues that may seem obvious to you are still very much appreciated!
Recording setup diagram here and below