Hi all,

I use SpectreRF for simulating a buck DCDC converter.

However this is one of the first time I use spectreRF so I am not sure I do it in the right way. I use it to determine the open loop response of the DCDC converter:

1-> Determine DC feedback level ensuring the right good output level
2-> run PSS simulation
3-> Determine PAC response in openloop.

This method gives quite good results when we compare transient response with phase margin computed previously. Problem is that PSS simulation is quite long as we need to wait for the DCDC output level to stabilize.

I have read one of your mail which tells that opening the loop is not a good thing, however I haven't found any equivalent for continous time stab analysis (IC5141 USR3) in discrete time analysis. Is it possible to calculate phase margin in close loop for a discrete time system with SpectreRF?

Regards
Matthieu

I have tried PSS + PAC to acquire the bode plot of only the power stage of a buck converter (e.g. dVout/dD where Vout is output of that buck converter and D is the duty cycle of a fixed frequency signal driving the PMOS of that buck converter).

So, the simulated result should follow the well-known and -accepted result of voltage-mode transfer function of a power stage of buck converter, such as with a complex pole located at the resonance frequency of LC of that buck converter.  However, the simulated bode plot shows the peak off from the theoretical location.

Anyone has faced similar problem as I did?

Thanks
Scottie