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Single Ended Input Signal Using INA 217

1282634
Prodigy 200 points

Other Parts Discussed in Thread: INA217

Hi, 
I would like to use INA 217 for my application. My application involves amplifying a single ended signal in mV range. I will set the IA to have a gain of 1500 and the maximum bandwidth is 50kHz. The output of the IA is connected to a single stage passive low pass filter (cut-off frequency 100kHz) before the single-ended output is connected to the ADC.
Since the application is to amplify a single ended signal, I use the configuration as shown in the Figure above. Instead of connecting the inverting input directly to ground, I noticed with other IA I have if I connect a resistor to the inverting input and then ground the inverting input, the IA output will have a much lower DC offset, the DC offset was reduced from 100mV to 50mV. The resistor has the same value as that in RC high pass filter connected to the non-inverting input. 
Can anyone confirm that it is the right way to use INA 217 for single ended signal?
Thank you.
  • 0
    Guru 21975 points

    1282634,

    The 1k resistor on the inverting input will help reduce the offset voltage due to input bias current. The INA217 is a very low noise amplifier. It very low noise is important in your circuit, you might benefit by reducing this resistance to a lower value (such as 100 ohms) and injecting a trimming voltage to adjust the offset.

    This circuit will require a dual +/- power supply.

    Regards, Bruce.