distortion of SW CAD III

[SkyChu]

I'm trying to simulate circuit by LTC SWCAD III . But the 3rd (Odd)distortion of input voltage source is too high when I use FFT simluation (V1, see attached files). the transient is ".tran 0 15m 1m 0.1u".
How can I reduce the distortion ?

 

[SkyChu]

The FFT:

 

[jcx]

have you turned off compression? expecting long sims of switching power regulator circuits LtSpice compresses the sim output data files by default - Tools>Control Panel>Compression - clik off all the boxes every time you open LtSpice

more recent versions accept a spice directive:

.options plotwinsize=0


in the fft menu i increase length to 131072 and use the Blackman window, keep averaging low or off(=1) since it is a digital low pass filter appiled to your data - i think mine defaults to 5

 

[DarkOne]

You have feedback attached only to "negative" half of the circuit

 

[SkyChu]

Thanks Jcx ! It can work !

 

[SkyChu]

You have feedback attached only to "negative" half of the circuit

Yes ! Is it "feedback" ? !


🙂

 

[thanh]

You have feedback attached only to "negative" half of the circuit

Ok! I have a agreement with Darkone
Skychu! you have to feedback attached only to "negaitve" half of the circuit