Error: Do Analyses: Iteration limit reached

[Mahesh0559]

Hi all,

I have designed a 0.2dB chebyshev low pass filter using TI WEBENCH electrical simulation tool with appropirate cutoff frequency, passband ripple etc. WEBENCH had suggested to use sallenkey topology to built the LPF of 8th order with 4 stages.

I have built the same in MULTISIM using opamp, resistors and capacitors. 

When i run the model (Run/Simulate), the model runs without any error. But when i try to do a frequency response of LPF,  i get an error message stating "Do Analyses: Iteration limit reached".

I saw some of the posts in the discussion forums, and tried their solution also like decreasing the shunt resistance value from E12 to E6, Use of a virtual power source etc.

I am also attaching the multisim file for your reference.

[jcham]

I was able to simulate the frequency response of your circuit by loosening the absolute error tolerance (ABSTOL) in the custom AC analysis settings from 1e-12 A to 1e-10. 

You can find this setting from the Analysis options tab in the AC Analysis settings. Under SPICE options, select Use custom settings and click the Customize.. button. From there you can specify a custom ABSTOL value.

I've attached a version of your circuit with the loosened tolerances. Just run AC Analysis with the saved settings in the attached file. 

Regards,

Jeff

National Instruments

[Mahesh0559]

Thanks Jeff,

I shall do it and come back.

Regards,

Mahesh Raja P