# active voltage divider?

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#### 7rots51

Hello

I want to conver a 0-10Vdc signal to 0-2.5 Vdc .I do it by two resistor (1%)as a passive voltage divider,Both the linearity is not good and in some region of full range the value of nonlinearity is high.If I use a .01% resistors the problem may be solved but the cost is too high.

I need to know is there an active solution with opamp for this problem ,(with using 1% resistors and precision opamps ) .

How to reach a precision divider with excellent linearity (max nonlin 2 mV at 10V)?

Regards

#### flatulent

I suspect that you are having loading effects of your network on the source and destination of your signal. Try buffering the input and output with precision op amps (a few uV offset and drift) in the gain of 1 configuration (output to - input). Use 1% resistors in your divider. Between them have a tapped resistor (trimpot) with the top and bottom to your divider resistors and the wiper to the output op amp. Use a trusted volt meter to adjust the wiper position for your desired 1/4 ratio. Have the top and bottom resistor about 99% of what you would ordinarily have and make the tapped resistor about 3% of the total. This way most of the divider resistor network is made up of low temperature sensitivity resistors and the temperature defects of the trimpot will be minimized. Don't forget to use large enough power supply voltages so that you do not exceed the common mode input range of the op amps.

#### bunalmis

##### Full Member level 5
I didnt understand where is the nonliner element at the passive voltage divider. (Load may be nonlinear.)

If you use opamp you can find more problem.

First problem is offset of opamp
and second you will use resistor again for opamp.

My idea, use high power resistor for divider and use in the small owen for stabil temprature conditions.