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Sending signals as current vs voltage, advantages?

ZeroSizeObject
If you are sending a signal through a PCB to a microcontroller, what is the preferred way to send it, current or voltage? What are the advantages and disadvantages of using either?
 
I ask because I have a signal that is corrupted would be quite devastating in the overall purpose of the device. I have experience more noise with the voltage based signal. And if I can not shorted the traces between the sensor (anolog) to the microcontroller, that is the better option?
 
Zero
  • 0

    As usally the world is not digital, hard to tell a absolute truth. But as you said, shorter traces will create less antennas to pick up noise.

    Current drive has a lot of benefits. Specially in generated noise. If you connect a current source to a virtual gnd input, ther will be no

    rise or fall times that can create any transients as the voltage is about zero.

    A current input also normaly need more energy in the noise signal to be disturbed.(also depends on impedans and input sensitivety)

    You can keep a voltage signal in good condition too if you have a low impedans source and low impedans input, but that will add

    some current consumption. If it is a slow signal you also may put some capacitive decoupling?

    Another way is to use a balanced signal that will make the imunity much better.

    Best regards

    /Mike

  • 0 in reply to Former Member
    Zero,
     
    If you are sending a signal from one side of a PCB to the other side, noise should not be a problem, unless the design of the PCB is poor and crosstalk between circuits is occurring.
     
    For sending weak signals over some distance in a noisy environment, a current loop over a balanced line is the best solution.
     
    Between an analog sensor and a digital system there should be an interface. Part of this interface could be a filter to separate the wanted signal from the noise.
    The interface should be located as close to the sensor as possible, to prevent interference,

    A digital signal between the interface and the microcontroller is less sensitive for noise

     

    If the sensor is using a different powersupply than the controller, the wires to the sensors powersupply could pick up a lot of noise.

    Sending the data via an optocoupler to the controller could help in that case.