Hi
I am working on a current to voltage converter to convert signals in the range of ~300pA into μV, i.e a gain of 10 to the 6.
I am using an ultra low bias current opamp ( LMP7721) with a 1GΩ resistor. I am having trouble testing this circuit as I cannot easily create a low nA/pA current. I have experimented with voltage dividers etc. but these seem to create impedance issues and my output swings to the negative rail.
I have also built a voltage to current converter as an input source using a 1MΩ to convert 100mV into 1nA for the input, however I cannot work out how to apply this current to the input of the I-V converter.
is this a valid test method or am I missing something simpler?
Best regards
Sam
I am working on a current to voltage converter to convert signals in the range of ~300pA into μV, i.e a gain of 10 to the 6.
I am using an ultra low bias current opamp ( LMP7721) with a 1GΩ resistor. I am having trouble testing this circuit as I cannot easily create a low nA/pA current. I have experimented with voltage dividers etc. but these seem to create impedance issues and my output swings to the negative rail.
I have also built a voltage to current converter as an input source using a 1MΩ to convert 100mV into 1nA for the input, however I cannot work out how to apply this current to the input of the I-V converter.
is this a valid test method or am I missing something simpler?
Best regards
Sam