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Thermal source connected with DC supply

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I'm currently attempting to simulate a circuit with various op amps connected together. The input voltage I'm using for the beginning amplifier is a low voltage DC supply. My problem occurs when I wish to induce noise into this input voltage. I have attempted to use the THERMAL_NOISE source connected with the DC supply, similar to having two different supplies in parallel. However, when I try to run the simulation I recieve a convergence error. The circuit runs completely fine with just the DC source or just the thermal noise source. When they're connected together something goes wrong. Has anyone ever had a similar situation or know of a good work around? Any help would be greatly appreciated.

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Hi Tenor,

 

Please post your Multisim file, I will see if I can fix it.

Tien P.

National Instruments
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I attatched the file below. Tried searching some more with no positive results.

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Hi Tenor,

 

Thank you for your post. Here are some links might be helpful to Thermal Noise Analysis in Multisim.

 

Noise Analysis using Analog Devices Operational Amplifiers

http://www.ni.com/tutorial/14516/en/

 

Configuring a Noise Analysis in Multisim

http://www.ni.com/white-paper/12789/en/

Chen_T
National Instruments
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Thanks for your reply. I'm not actually looking to do a noise analysis on the circuit components themselves. I'm wanting to view running results of the circuit with noise injected into the system. It's possible I've missunderstood the noise analysis simulation, but I'm fairly certain that won't give me the results that I'm seeking. 

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Solution
Accepted by topic author tenor07

When you have two sources n parallel, it can cause convergence error is a SPICE.  To fix the problem add a tiny resistor to between the sources.

 

I don't think the noise source will make a difference in this case, most SPICE models doesn't model noise.

 

Tien P.

National Instruments
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