This thread has been locked.
If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.
Hello there.
I am stuck in a rather bizzare phenomenon while simulating a simple analog circuit in TINA-TI. We all are aware that resistors introduce their own noise into the system, i.e., the higher the resistances the higher the Johnson noise. I am trying to perform a simple simulation by varying the input resistance of a sinple elevel-shifted inverting amplifier and monitoring the input noise in the system. The circuit is as follows.
And, when I try to varry P1, this is what I get:
The input noise should increase as P1 is increased, shouldn't it?
And why is the noise in the range of KV/√Hz?
I definitely must have missed something in the settings!
Hi Abbas,
keep an eye on the common mode input voltage range. And don't drive the output into saturation.
So, only a very limited setting range of P1 is allowed.
Kai
Thank you for your response, kai klaas69. Really appreciate it.
It seems I missed some details in my original post.
I am not varying the potentiometer setting. It is fixed at 50%. I am varying the overall value of P1. And, since the potentiometer setting is fixed at 50%, the common-mode input voltage range should not be a concern.
The objective here is to study the influence of the efective value of P1 on the overall system noise.
Yes, this is how it should be!
Really appreciate your efforts.
But why am I getting the other way?
Thank you for your efforts, kai klaas69. Really appreciate it.
I am afraid why such a huge difference in the results by simply adding a few capacitors?
What if I need to check the effectiveness of difference capacitor cofigurations in noise reduction and find the optimized value? I should be able to do that!
Also, when you menton the expression for the noise calculation, do you mean that I need to explicitly specify this formula somewhere in order for the noise calculation to be correct? This shouldn't be the case!
Did the trick!
The excessively high input noise values must have been because of the large input impedance of the op-amp. How silly of me to have missed it!
Thanks a lot, kai klaas69. That really helped.