Hi,
The first that comes into my mind:
* Why do you want to amplify the signal ... before the cable?
I assume you want to improve signal to noise. If so, then I don't think there is much benefit. Even in best case you gain only a couple of dB. And only if there is
differential noise along the cable. Mind: You might expect
common mode noise along a twisted and shielded cable. --> thus I don't see much benefit
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When I see your schematic there is:
* a differential signal source
* a differential to single ended amplifier
* a single ended to differential amplifier
--> Why the "single ended" mode?
Why don' t you just use a fully differential amplifier? Differential_in differential_out?
You even may build such a thing with two standard amplifiers: ...the left side part only -with greenish backcolor.
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Regarding Ground wiring:
In opposite to single ended wiring: here - with differential wiring - the GND wiring is not very important. Ideally there is no GND current and GND does not act as signal reference. The GND just acts to prevent common mode voltage from runaway.
You may connect GND anywhere.
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My recommendation:
I'd use no amplifier, but send the already differential signal without amplification across the wire. Use a twisted pair wire with good shielding. Thus you also need no power supply (for the amplifiers) at the sensor side.
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In every case: use good differential mode filters as well as single mode filters to maintain best signal to noise.
Klaus