A simulation problem of CLASS-D

[lqy]

how to simulation class d stability

Does anyone know how to simualte the bandwidth of the class-d with spice, because the PWM in class-d is a digital part and the feedback is also digit pwm signal, so I don't know how to obtain the bandwidth and how to verify the stability of class-d amplifier.
I hope that the experts can help me, thanks.

 

[goodboy_pl]

the simple way is small signal modelling of the PWM and switches and AC simulation!
for most accurate results u must run several transient simulations,
use a small signal signal source (sin wave in series with a DC voltage source ) as input signal then run transient simulation and at steady state find amplituse and phase of the super imposed sin wave at output by fft, then plot the simulation points from several try in matlab, this is very similar to ac simulation at least below fs/10.

BEST!

 

[lqy]

Hi，goodboy_pl, thank for your answer.
I'm new in this field, I have tried the first mothod you talked about, but I have some

problems to use this method:
1. first, I don't know how to model the PWM switches.
2. second, because the feedback is taken from the switches output(It is before the LPF,

so the feedback is pwm digital signal) and connected to a integrator, if we model the

PWM switches, how to deal with the feedback pwm signal?

for the accurate simulations method with transient, could you give more detail

explaining?
I'm looking forward to your answer, thanks very much.

 

[lqy]

Help me, please!