How to make Current to Voltage converter

Question

I am working on level sensor which give output of 4-20 mA. I have to feed output of level sensor to an ADC of a micro-controller, to do so I have to convert it from current to voltage.Voltage range needed is 0-1.8 Volts.

So I have gone through some circuits below:

enter image description here

I want to know which would be much more suitable to be used with ADC of micro-controller.

You should also consider the range of voltage the ADC supports and then design a converter depending upon resolution and range that needs to be supported. — WedaPashi, Jul 01 '15 at 09:46
Plus, consider what the output impedance of the sensor is, i.e. what voltage range it can output. — JimmyB, Jul 01 '15 at 09:47

score 3 · Accepted Answer · answered Jul 01 '15 at 09:47

They both work but the simple resistor is less prone to inaccuracy because the op-amp will introduce voltage offset errors and possibly leakage current errors. Bandwidth of the op-amp may cause other problems if the signal is high frequency compared to the gain-bandwidth-product of the op-amp.

On the other hand, the thing that produces the 4/20 mA signal may prefer to see a short circuit as an input and the op-amp offers this by virtue of it being a virtual earth at the inverting input.

How to make Current to Voltage converter

1 Answers1