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| Diffrential amp design |
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| ali_asadzadeh:
Hi, I have an old design and it's working perfectly, it's used in an Electromagnetic Flow Meter, the input sensor differential potentials is in uV ranges. Now I want to redesign it with newer and cheaper parts, because I want to increase the performance, and use lower priced parts, also It would be very beneficial if i could do it in a single supply config and also If I could do it fully differential and remove the GND from the input sensor, currently I'm using AD620 part, But for the new design I prefer using normal op-amps or use Chinese parts! any Ideas are highly appreciated. If I could do it under 1$ for total op-amps it would be perfect. |
| moffy:
Because of the micro volt signal level, I would go with a true differential amp as your AD620, or risk getting swamped by low cmrr. But you don't need two, the second can be just a straight opamp. |
| Zero999:
--- Quote from: moffy on January 23, 2020, 08:10:17 am ---Because of the micro volt signal level, I would go with a true differential amp as your AD620, or risk getting swamped by low cmrr. But you don't need two, the second can be just a straight opamp. --- End quote --- Yes, it's not possible to do this with a cheap op-amp, not without spending more on precision resistors. Accurately measuring microvolt signals is incompatible with low cost. |
| magic:
You can eat your cake and have it too: buy AD620 from AliExpress 8) |
| ali_asadzadeh:
::) :P :-[ :-X we have made a lot progress in the industry, why stick to some old and pricey tech! Can a few these zero-drift Precision OpAmps come in handy? Like GS8333 https://lcsc.com/product-detail/Precision-OpAmps_Gainsil-GS8333-TR_C431326.html |
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