Effect of bias currents on output of an op-amp?

741 comes in various grades. Download the data sheet for values. Values run from 30 to 500 nA.

Bias current is about 100 nA, offset current about 20 nA

The effect depends on the equivalent resistance seen by the inputs. If that is 10 kΩ, then the error is 10kΩ x 100 nA = 1 mV. In other words, the error due to the bias current is equivalent to a 1 mV voltage offset at the input.

If the input R is 100kΩ, then that error is 10 mV

If both inputs have the same 100kΩ equivalent resistance, then the errors partially cancel, and the offset current comes into play. In this case 20 nA x 100kΩ = 2 mV

The effect of that error on output varies with the circuit and the gain. If gain is 100, for example, with 100kΩ input resistors, the 2 mV error would add to the input offset voltage (say it's ±3mV) for an input total error of 5 mV, which produces an output error of 500 mV. That is worse case, and polarity is not known, could be + or –

You can minimize these errors, many ways:

use the best grade 741

Use a better opamp

keep input resistance low

keep input equivalent resistance the same for the two inputs.

Add a way to adjust out the offsets

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Are you connecting the enter instantly to the non-inveting enter? that's senseless, because the enter is a digital floor, as you well-loved. A digital floor has no capacitance, only as an precise quick would don't have any capacitance both. So there's a resistor, on the least, between the enter and the opamp, and that's the capacitance of that element that determines the circuit enter capacitance. the option probability is that you're operating at a frequency severe passable that the opamp loop receive is low adequate so as that the enter is now no longer a digital floor. this does no longer take a lot, it will be as low as 10 kHz for some circuits. .