Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Voltage Dividers

  1. Feb 5, 2006 #1
    Is it possible to design voltage dividers that do not primarily use resistors. Could you make a <1 voltage gain amplifier? What is usually done in real applications?

  2. jcsd
  3. Feb 6, 2006 #2


    User Avatar

    Staff: Mentor

    If you are working with an AC signal, you can use reactive elements like inductors and capacitors to form a voltage divider. However, keep in mind that you may get some phase shift in the divided output voltage, depending on what mix of components you use, and you may get a frequency-dependent behavior, as in an L-C lowpass filter configuration. Also, series capacitors are not generally used alone to form AC voltage dividers, since the DC voltage in the middle of two series-connected caps is not really defined by anything (except leakage current). Large value bleeder resistors would generally be placed around series-connected caps like that.

    You could also make an active transistor voltage divider, I suppose. Although you would most likely be using resistors in the bias networks for the transistors.

    As for an amplifier with gain <1, yes, that is sometimes done. Usually it is done as part of buffering a signal. You use an amplifier that has a high input impedance compared to the output impedance of the source voltage, so that the signal is not distorted much by going into the input of the amplifier. And the amplifier takes power from the power supply to generate a copy of the input signal at the low-impedance output of the amp. This low output impedance of the amp allows it to drive moderate input impedance loads, again without much distortion on the signal. The overall gain through such a buffer amp can be 1, or >1 or <1, or even adjustable, depending on the application.

    What is the context of your question? We can probably give you a better answer if we know what your intended application is.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook