# percentage gain for op-amps

Discussion in 'Homework Help' started by lemon, Mar 14, 2010.

1. ### lemon Thread Starter Member

Jan 28, 2010
125
2
Hi:
I am trying to calculate the percentage error for an inverting and non-inverting op-amp.
For the inverting op-amp the error is 0.7V. This is the difference between the theoretical gain -Rf/Rin=100k/10k=10, and measured gain Vout/Vin=16.6/0.2=9.3

error is 0.7V.
Percentage error = 18.6/2 =9.3
0.7/18.6x100=3.8%
0.7/2x100=35%
3.8%+35%=38.8%
0.338x9.3=3.1V
For the non-inverting op-amp the error is 0.1V.
Percentage error = 3.80/2 =1.9
0.1/3.8x100=0.03%
0.1/2x100=0.05%
0.03%+0.05%=0.08%
0.0008x1.9=0.0015V

Have I done this right?

thank you

2. ### Bychon Member

Mar 12, 2010
469
41
16.6/0.2 = 83 not 9.3
I think you meant 16.6/2.0 = 8.3
The calculated voltage output is 20
The real voltage result is 16.6
16.6/20 x 100 = 83%
100-83 = 17% error

for 18.6/2 = 9.3 demonstrated gain
10 is calculated gain
9.3/10 x 100 = 93%
The error is 7%

That's the end. The error is 7%

Then you divided the voltage error by the real output voltage
Then you divided the voltage error by the input voltage