The procedure of the simulation of the Harmonic Distortion

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Dear All, thank you for reading this topic. I just design an OTA and I will conect it to a capacitor to build a lowpass filter. Then I will put a 100mV sine signal at the input and want to see the harmonic distortion at the output. Does anyone show me the procedure that how can I get the result? A sample is put in the attchment and that is what exactly I want.Thank you so much!
 

Re: The procedure of the simulation of the Harmonic Distorti


When you want to see the distortion, you have to perform a transient simulation or a time domain measurement in order to evaluate the output waveform.
If you want to measure the distortion you have to measure/simulate the harmonics and to calculate the THD.
 

Re: The procedure of the simulation of the Harmonic Distorti



Hi,thank you for your reply, could you tell me the first situation, when I use the "dft"to calculate, how can I get the "20log" Y axis? Because I can just get a "log" but cannot get "20log".Thank you!
 

Re: The procedure of the simulation of the Harmonic Distorti

bhl3302 said:
Hi,thank you for your reply, could you tell me the first situation, when I use the "dft"to calculate, how can I get the "20log" Y axis? Because I can just get a "log" but cannot get "20log".Thank you!
Click to expand...

It depends on the simulator engine you are using.
 

Re: The procedure of the simulation of the Harmonic Distorti

From the plotter it seems to me that you're using Cadence. If so, what simulator are you using, spice or spectre??

diemilio
 

Re: The procedure of the simulation of the Harmonic Distorti

diemilio said:
From the plotter it seems to me that you're using Cadence. If so, what simulator are you using, spice or spectre??

diemilio
Click to expand...

Thank you man, I have solved the problem, thank you all the same!
 

Re: The procedure of the simulation of the Harmonic Distorti

then post the solution as well. it will be good for some one else.

hock
 

Re: The procedure of the simulation of the Harmonic Distorti

hock said:
then post the solution as well. it will be good for some one else.

hock
Click to expand...

OK，after using transient analysis to get the signal you want, you can use the calculator to do the "dft", before clicking on the "evaluation"button, you can click"20dB" again to get a log Y axis.
 

Re: The procedure of the simulation of the Harmonic Distorti

[quote="bh, you have to perform a transient simulation or a time domain measurement in order to distortion you have to measure/simulate the harmonics and to calculate the THD.[/quote]


Hi,thank you for your reply, could you tell me the first situation, when I use the "dft"to calculate, how can I get the "20log" Y axis? Because I can just get a "log" but cannot get "20log".Thank you![/quote]

in cadence calculator, use dB20 fuc to plot your DFT results

that is dB20(DFT("V(....

good luck~~
 

Use the THD calculator...
 

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