Noise and AC analysis (operating point not found)

Tariq hussain

Prodigy 30 points

Dear All,

Please, help me to analyse the attached circuit. I want to do the frequency analysis.

U1.de (Operating not found)4188.inverting op amp.TSC

Kind Regards

over 12 years ago

0 Nikhil Gupta (Product Folder Models) over 12 years ago

TI__Mastermind 39210 points

Hi Tariq,

The reason why you are getting a DC Operating point convergence error is because you have a capacitor connected in series with the input. For DC Bias point calculations, all capacitors are open so the input to the OPAMP is floating. The way you can resolve this is by clicking on the capacitor in the input path and change the Rpar (which is a parasitic resistor connected in parallel to the cap) from Infinite to 1G. This will resolve the convergence error. I also changed the probe markers and reset the input to the default sine state. Please see attached and let me know if you have any other issues.

4530.inverting_op_amp_mod.TSC

Best regards,

0 Tariq hussain over 12 years ago in reply to Nikhil Gupta (Product Folder Models)

Prodigy 30 points

Thanks, a lot Mr Gupta,

It works fine. Would you please help me to achieve the 1dB compression graph. I don't know how to plot it.

Your help is very appreciated.

Kind Regards,

Tariq

0 Nikhil Gupta (Product Folder Models) over 12 years ago in reply to Tariq hussain

TI__Mastermind 39210 points

Hi Tariq,

When you run the AC Analysis (Analysis --> AC Analysis --> AC Transfer Characteristics), you will get the Bode Plots. From the Bode plot, you can see the point at which the Gain is 1db below nominal.

Best regards,

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Noise and AC analysis (operating point not found)