OPA392: Looking for a front end circuit to measure nono amp current

Rocky Chen

Part Number: OPA392
Other Parts Discussed in Thread: LMP7721

Hi Expert,

I am looking for a OpAmp front end circuit for my customer. Target current to measure, range from 1nA to 100nA. We will also select an ADC followed OpAmp circuit. It looks the higher gain required, would you please recommend a OpAmp circuit?

Thanks a lot!

-Rocky

over 3 years ago

0 Raymond Zhang1 over 3 years ago

TI__Mastermind 48336 points

Hi Rocky,

Is this photo diode current measurement application from 1nA to 100nA? What is the BW of current input signal? Please describe the design requirements for the application.

Please take a look at the following thread and application note, and I will help you to simulate a circuit tomorrow.

https://e2e.ti.com/support/amplifiers/f/14/t/789221?tisearch=e2e-sitesearch&keymatch=nano%25252520amplifier

https://www.tij.co.jp/jp/lit/an/snoa942a/snoa942a.pdf?ts=1611555714783

https://www.ti.com/lit/an/sboa122/sboa122.pdf

Best,

Raymond

0 Raymond Zhang1 over 3 years ago in reply to Raymond Zhang1

TI__Mastermind 48336 points

Hi Rocky,

Since you did not provide us with design requirements, I put a TIA circuit together based on photodiode application. Photo sensor's current range is from 1nA to 100nA and LMP7721's output range is from 10.36mV to 1.0V.

/cfs-file/__key/communityserver-discussions-components-files/14/LMP7721-TIA-App-01262021.TSC

If you have additional questions, please let me know.

Best,

Raymond

Amplifiers

Amplifiers forum

OPA392: Looking for a front end circuit to measure nono amp current