Can you understand a definition of THD, SNR, SINAD ?
THD is not ratio of funadmental-component and 3rd-order-harmonic.
Don't rely on Direct Plot Form in Cadence ADE blindly.
Use skill functions directly with understanding THD definition surely.
1. using PSS analysis
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It shows it in the form of 10 vertical straight lines because I have set the no. of harmonic as 10.
I am taking the difference between the first harmonic and third harmonic which shows 58 dB.
If you use Shooting-Newton-PSS, no. of harmonic as 10 is enough.
However, if you use HB-PSS, it is too few.
2. Second option is I am doing transient analysis.
On this transient response of the fully differential output I apply DFT fusing calculator
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I again get vertical lines as harmonics this time I get 53 dB which is the difference between first and third harmonic.
3. Third option is I have done transient analysis
----apply THD using calculator ---take 20 dB---
This time it doesn't show waveform, it shows in form of numbers -10 dB, which I think is wrong.
Don't use function without understanding its definition.
"thd()" returns value as "%".
So 20*log10(10**(-10/20)/100)=-
50dB
I havent placed any port in my circuit
Why do you require "port" ?
The only source is the input sources of differential amplifiers.
Do you surely set common mode bias ?
Can you understand the followings ?
There are two modes regarding input drive, common mode and differential mode.
Also there are two modes regarding output, common mode and differential mode.
Any of three could be correct, as far as you can understand THD correctly and you can do simulation correctly.
i ALSO want to calculate SNR.
There is no SNR option in calculator?
Anyother way to find SNR?
Simply calculate SNR based on its definition.
Here noise power can be evaluated by PSS/Pnoise.
Distortion's power can be evaluated by PSS.
If you would like to use Transient Analysis, you have to use Transient-Noise Analysis.
Noise power which is evaluated by conventional Transient Analysis is no more than numerical noise not physical noise.