Opamp Expert Opinion needed

Audioguru again

Joined Oct 21, 2019
2,968
Starting at the bottom of your list, the input bias current and input resistance of many opamps prevents using an Rin and Rf less than maybe 200k ohms. For an Rin and/or an Rf of 11M then select an opamp with Jfet or Mosfet inputs that use no bias current and has an extremely high input resistance.

In the middle of your question is an Rin and Rf as low as 10 ohms which is crazy because a power amplifier, not an opamp is needed. Most opamps are overloaded with less than 2 thousand ohms as shown on their datasheet.

At the beginning of your list is an Rin and Rf of 11k which will work with many opamps but check the datasheet to see if the output current is high enough to drive 11k ohms.
 

Thread Starter

mishra87

Joined Jan 17, 2016
906
Starting at the bottom of your list, the input bias current and input resistance of many opamps prevents using an Rin and Rf less than maybe 200k ohms. For an Rin and/or an Rf of 11M then select an opamp with Jfet or Mosfet inputs that use no bias current and has an extremely high input resistance.

In the middle of your question is an Rin and Rf as low as 10 ohms which is crazy because a power amplifier, not an opamp is needed. Most opamps are overloaded with less than 2 thousand ohms as shown on their datasheet.

At the beginning of your list is an Rin and Rf of 11k which will work with many opamps but check the datasheet to see if the output current is high enough to drive 11k ohms.
Hi A,
Thank you very much for your detailed explanation.

Regards,
M
 
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