3 channels ,PWM , resonance frequency

[plassma]

Please help me to find a   PWM  solution ( evaluation boards /power module) with this caracteristics :

- control/adjust   frequencies from software

- feeadback option   /spectrum analyzer to find resonance frequency

-3 channels with difrent  frequencies   (42.8 KHz, 21.4 KHz and 10.7 KHz )

- Adjustable Duty cycle  /pulse with 2.5%,5%, 10%  ,    fall time     <=20nS

-Up to 500 Watt

[Henrik_Volkers]

From your picture, I would go with a AWG if 4 levels should be possible,

or a simple digital output ...  

followed by a line driver , depending on the needed output power (and maybe a comperator as preamp)

If you try to create the PWMs with three 555 your phase will be unknown.. (OK, it's possible to oscillate them in sync... but why do that if software can do it much better 😉 )