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I generate an analog voltage from PIC microcontroller output. I want to transmit this analog signal to maximum distance as much as possible using single wire. I have non-inverting OPAMP at the output of PIC pin. enter image description here

Which configuration best for this maximum driving purpose?

  1. Without OPAMP, direct driving from PIC
  2. Unity gain OPAMP, R45=open, R46=0ohm
  3. With some values of R45 and R46. Noninverting topology.
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  • \$\begingroup\$ Could you please elaborate on "single wire"? Even with simple voltage signals there is the common 0V, which is also your "second wire". Longer distances normally employ differential ("current loop") transmission. Can you specify your signal and noise environment? \$\endgroup\$
    – devnull
    Commented Feb 19, 2021 at 11:29
  • \$\begingroup\$ Yes the signal is referenced to Ground which is second wire. Signal will be transmitted in a factory enviroment. It cant be very clean. \$\endgroup\$
    – Berker Işık
    Commented Feb 19, 2021 at 12:07

1 Answer 1

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Without OPAMP, direct driving from PIC

This is the worst option.

2 and 3 will probably have the same performance. Using a buffer after amplification might be slightly better.

Personally, I'd prefer a 4-20mA current loop.

Even if you increase the signal voltage and drive the transmission line with a closed-loop power amplifier, there is still a risk of voltage drop at the end node. And you may not be able to calibrate each time to "recover" the drop. If you drive the line with current, all you'll need is a resistor at the end node to convert the current to voltage.

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  • \$\begingroup\$ 4-20mA needs more than this circuit. I`m searching which one is better using this simple circuit topology. \$\endgroup\$
    – Berker Işık
    Commented Feb 19, 2021 at 12:11
  • \$\begingroup\$ Also requirement of the signal is voltage output. \$\endgroup\$
    – Berker Işık
    Commented Feb 19, 2021 at 12:46
  • \$\begingroup\$ @BerkerIşık 4-20mA needs more than this circuit. Of course, it does. But it's better, stronger and more stable. Also requirement of the signal is voltage output. If you put a respective resistor at the end node you'll get voltage. Anyway, I'm editing my answer. \$\endgroup\$
    – Rohat Kılıç
    Commented Feb 19, 2021 at 13:35

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