# Op-amp

Discussion in 'General Electronics Chat' started by atlas, Jul 29, 2006.

1. ### atlas Thread Starter Member

Jul 18, 2006
28
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Hi guys,

I'm just wondering if there's an op-amp that can amplify few micro volts to volts...As I need to design an op-amp integrator that can amplify few micro volts to volts... Please if there's just tell me the model name.. Thanks a lot ...

2. ### beenthere Retired Moderator

Apr 20, 2004
15,815
283
Hi,

Could you quantify your requirement a bit better? How many microvolts, and how many volts? It will be easier if you use multiple devices, rather than one, considering the amount of amplification.

I believe you might want to do your amplification, and then integrate the result. Do you have a circuit you can post for commentary?

3. ### atlas Thread Starter Member

Jul 18, 2006
28
0
I need to desgin an integrator where the in the put to this integrator will be in terms of micro volts.. For example, 60 micro volts of input and the integrated result would be 6 volts.This means the input will always be in terms of microvolts and the integrator should be able to amplify it to volts .Just like when ideal integrator works.

4. ### beenthere Retired Moderator

Apr 20, 2004
15,815
283
Hi,

Integration is the product of the amount of change in an input over time. See http://www.allaboutcircuits.com/vol_3/chpt_8/11.html for more on this. DC signals integrate to zero.

Your function is amplification - making a 60 microvolt input into a 6 volt output. I would go for a gain of 100,000 in two steps - 100 and 1000. An OPA2134 dual op amp might do very well.

5. ### atlas Thread Starter Member

Jul 18, 2006
28
0
Yeah what you said is correct, but my input keeps changing, it's not constant coz if it's constant then my op-amp will go into sautration. My input is in terms of micro volts and keeps changing.. I would like to go for a gain of 100,000 but do u think there's a way to do that in one step rather two steps??

6. ### beenthere Retired Moderator

Apr 20, 2004
15,815
283
Hi,

You can always try to get there in one step. Look for an op amp with extremely low offset current, as that will cause output errors.

With proper feedback, a static input should not cause your op amp to sautrate. perhaps you could post a circuit to help the discussion?

May 16, 2005
5,072
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May 26, 2004
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9. ### atlas Thread Starter Member

Jul 18, 2006
28
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Thanks a lot guys. I found an excellent op-amp with very low offset voltage (op297)..

I'm wondering if there's Controlled Current Source IC compnent in the market.. If you know please let me know.....

10. ### atlas Thread Starter Member

Jul 18, 2006
28
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Is there an op-amp with offset voltage of nanovolts?? As I tried to look for this type but what I found was in terms of microvolts.. Thanks a lot

11. ### pebe AAC Fanatic!

Oct 11, 2004
628
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Have you looked at chopper stabilised op-amps?

12. ### atlas Thread Starter Member

Jul 18, 2006
28
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yeah I found it.. Thanks a lot ...

13. ### atlas Thread Starter Member

Jul 18, 2006
28
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I'm looking for a current controlled source, but I cannt really find any.. Does anyone know about it??