Just a quick question:
Regarding the chopping frequency, for a bandwidth of 1MHz, I selected a chopping frequency of 5MHz. I figured that it has to be greater than the bandwidth to avoid transformer saturation.
Unfortunately, I wasn't able to find any analog switch (in DIP flavor) fast enough to switch at 5MHz. Any suggestions ? How about using fast mosfets as analog switches ?
7roots51: I have been using isolation products before going into this (analog devices) but the problem is that their bandwidth is limited and the cost is generally high.
I've taken appart a digital oscilloscope input board and I found that they were not using any isolation products at all. They are using transformers and lots of signal conditioning circuitry. I also believe they must be chopping the signal too (I guess from the ICs involved in the board). I assume it is still the cheapest and best solution.
Mariano