I have the following questions regarding different types of isolation techniques:

  • What are the major differences between Channel-to-Ground & Channel-to-Channel isolation techniques?
  • Are all Ch-to-Ch isolated devices also Ch-to-Gnd isolated?
  • Is there ever a scenario where you would chose Ch-to-Gnd over Ch-to-Ch isolation given all else equal?
  • Do either of the two techniques reduce the effects of crosstalk? If so, how and which one is better?
  • 1
    \$\begingroup\$ This is a question about semantics rather than electrical engineering. It would help if you had an example in mind you could share. Isolation could mean galvanic isolation or AC crosstalk minimization. Sorry for being a pedant. \$\endgroup\$ – Andy aka Sep 25 '13 at 18:58
  • \$\begingroup\$ First the meaning of channel should be clarified properly. \$\endgroup\$ – AKR Sep 27 '13 at 17:38

It sounds like you're talking about an oscilloscope or something similar. In that case, the channel-to-channel isolation describes the isolation between each channel and every other channel. The channel-to-ground isolation describes the isolation between each channel and ground. These are different, but related, concerns.

Channel-to-channel isolation describes how much voltage differential there can be between two inputs to the scope.

Channel-to-ground isolation describes how much voltage there can be between any input and the ground input to the scope, usually through the power connector.

The "techniques" involved aren't different at all. When two things are to be isolated, make sure there aren't any conductive paths between them, and make sure that all barriers between them (optocouplers, transformers, air distance, creepage distance, insulation, etc.) are rated for the isolation voltage you want.

Now, if all channels are isolated from each other, they must also all be isolated from ground; if they were all referenced to ground, they would all also be referenced to each other! It is, however, possible to have all channels isolated from ground while still being referenced to some other common node. This scenario can be useful, depending entirely on what it is you want to measure. If all the signals being measured are referenced to the same voltage, which is not earth, then your scope also having isolation to ground but not channel-to-channel would be fine.

As for crosstalk, that would require more details about what you're doing. I don't think there's a general answer there.

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