how to generate phase shift pwm ltspice

Thread Starter

AKA7A

Joined Jun 20, 2021
5
I'm trying to generate a phase shift PWM signal but no luck , I've followed this video
, I always get different results , especially he uses a library of a summer .
any one knows how to generate phase shift pwm signals. Thx!
 

Thread Starter

AKA7A

Joined Jun 20, 2021
5
hi AKA,
As you say, he is using a Summing Model, is the Lib file for this Σ on his website.?

E
There is no website , he just show some demonstration on youtube, but no specification on the symbol of summing and no no specification on duty 2.Thx!
 

crutschow

Joined Mar 14, 2008
28,215
What's the difference between phase-shift PWM and normal PWM?
the PWM signal is always 50% and it's the same PWM signal but with added phase (0-360°) , in this example, the phase is proportional to the duty cycle.
Then that's obviously not PWM (Pulse Width Modulation), it's phase shift modulation, an entirely different animal.
 

Alec_t

Joined Sep 17, 2013
12,320
the PWM signal is always 50% and it's the same PWM signal but with added phase (0-360°) , in this example, the phase is proportional to the duty cycle.
? If the PWM duty cycle is a constant 50%, then by this definition the phase will also be constant.
 

crutschow

Joined Mar 14, 2008
28,215
If the PWM duty cycle is a constant 50%, then by this definition the phase will also be constant.
The duty-cycle may momentarily change slightly when the phase is changed, but certainly you can have a 50% duty-cycle with a phase different from a reference signal of the same frequency (such as a PLL extraction of the clock frequency).
Seems similar to phase-shift-keying (PSK) modulation.
 
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