zoulzubazz
Member level 5
Hi guys,
I am trying to measure a small current (near DC, ~1-10nA) using a 12 bit ADC. The obvious way to do this is using a transimpedance amplifier (TIA). To obtain a mV range output from the TIA, the feedback resistor has to be atleast 1MOhm.
I am worried about the voltage and current noise gain due to the large feedback resistance.
For example, an amplifier with voltage noise as low as 100nV the noise is gonna be 10mV (NoiseGain = 1+1M/Rin, Rin=100 because of timing constrains on the circuit). Is there any way to get around this issue. Is making ratiometric measurement with the ADC a good idea? Thanks very much.
I am trying to measure a small current (near DC, ~1-10nA) using a 12 bit ADC. The obvious way to do this is using a transimpedance amplifier (TIA). To obtain a mV range output from the TIA, the feedback resistor has to be atleast 1MOhm.
I am worried about the voltage and current noise gain due to the large feedback resistance.
For example, an amplifier with voltage noise as low as 100nV the noise is gonna be 10mV (NoiseGain = 1+1M/Rin, Rin=100 because of timing constrains on the circuit). Is there any way to get around this issue. Is making ratiometric measurement with the ADC a good idea? Thanks very much.