How to simulate Large signal bandwidth of amplifier

Dear Shawn,

Thanks a lot, that was a wonderful help, it is working now perfectly :)

I could now simulate the large signal bandwidth of my circuit. For the purpose of the test I have verified it with a simple single poleLPF circuit,

I have defined a math function to calculate the gain in db by dividing the peak-to-peak value of the output signal to the input as you can see from the image below, the clip function helped me to take the clean part of the signals.

One thing remaining for this approach is how to plot the phase response of the circuit from this time domain simulation.

Thank you very much once again and I do appreciate your kind help and support

Regards

Dear Senan,

Senan said:

I could now simulate the large signal bandwidth of my circuit. For the purpose of the test I have verified it with a simple single poleLPF circuit,

I have defined a math function to calculate the gain in db by dividing the peak-to-peak value of the output signal to the input as you can see from the image below, the clip function helped me to take the clean part of the signals.

Excellent and very good work Senan!! There are other means to more precisely determine the large-signal gain, but if the amplitude of your input and output signals are sufficiently large with respect to numerical noise, and your amplifier does not produce significant harmonic distortion, and the accuracy requirement for your transfer function/bandwidth estimate is under 1 dB, your method is probably fine.

Senan said:

One thing remaining for this approach is how to plot the phase response of the circuit from this time domain simulation

The phase response can be estimated using a series of time domain measurements of the normalized input and output waveforms if you're up for another "challenge". I will send you an example shortly.

Shawn

Dear Senan,

ShawnLogan said:

The phase response can be estimated using a series of time domain measurements of the normalized input and output waveforms if you're up for another "challenge". I will send you an example shortly.

I've completed an example of the methodology using a 1 MHz lowpass single-pole filter and documented a few notes on the masher in which the phase is computed from the normalized input and output waveforms (assuming sinusoidal). They may be a bit brief, but I was trying to get you something quickly to consider. I hope this helps.

Shawn

transfer_function_gain_phase_1 MHz_example_sml_021423.pdf

Dear Senan,

I took some time to better explain the algorithm to determine the large signal transient response when the input and output waveforms are nearly sinusoidal and corrected one error in my prior note. Please  ignore the prior document to avoid any confusion and refer to the following document:

If I try to include this as a link, it will be flagged as spam, so I have to include it as a graphic - sorry! However, if you just enter the first part of the address into your browser and append it with:

/s/z7bljbf3l539u87/transfer_function_gain_phase_1%20MHz_example_sml_021523v1p1.pdf?dl=0

it may be less "painful" to access the note. My apologies for the added effort Senan!

Shawn

Dear Senan,

I updated the note to include the manner in which the gain was computed to version 1.2. Unfortunately, the address was changed even thought I attempted to keep it the same. The last segment of the updated note address (and correct address) is:

/s/9ok4tyy8iz8sp4i/transfer_function_gain_phase_1%20MHz_example_sml_021623v1p2.pdf?dl=0

Shawn

transfer_function_gain_phase_1 MHz_example_sml_021623v1p2.pdf

Dear Shawn,

I am so grateful for your great help and dedicated time to answer my post. I will soon recover my access to Cadence after my vacation and give you feedback on your suggested method.

Thank you very much once again 

Best Regards

Dear Senan,

Senan said:

I will soon recover my access to Cadence after my vacation

I just hope it is somewhat helpful - but vacation must come first Senan! Enjoy!

Shawn