Problem with OpAmp Simulation in LTspice

[mechguy]

Hello,

Recently I have some problem with simulation in LTspice for operational amplifier (inverting amplifier) circuit. The source voltage and first resistance before opamp is 9 V and 3.6m ohm. The second resistance is 1k ohm. So, the expected output voltage should be

Vout = 9 / 3.6m* 1000 = 2.50 V

But instead, it shows the value of 1.21 V after running the simulation.

I have attached my LTspice drawing here. Kindly appreciate any help and suggestion to me. Thanks in advance! ;-)

 

[LvW]

I have three recommendations:
* Check your gain formula
* Realize that 3.6m means 3.6 milliohms
* Become familiar with problems of single supply (or use double supply)

 

[FvM]

This gain formula makes more sense for an inverting amplifier

Vout = -(9 / 3600* 1000) = -2.50 V

You'll notice that neither 3.6m nor 3.6Meg are correct, also the expected output voltage is negative, which leads to the dual supply point addressed by LvW.

 

[milind.a.kulkarni]

In my view it shoud be 3.6K i.e. kilo-ohm for the formula that you said .....as FvM pointed out your OPAMP is working in Non-inverting mode thus the O/P should be negative.....

Good Luck

 

[KerimF]

What you got as Vout = 1.21V is the lower saturation voltage of LT1001 for an ouput load of 1K connected to 9V (since Vin- voltage is close to 9V due to the 3.6 milliOhm).

 

[mechguy]

Finally, my problem is solved:
1. It's my carelessness for the equation, yes it's 3.6k.
2. I've changed my voltage supply inversely.
3. I apply double voltage supply to OpAmp.

The output voltage is + 2.5V. Thanks for your helps!