sheldon wrote on Jan 31st, 2008, 8:08am:Dandelion,
By the body diode are you referring to the body-drain diode or are you
using a triple well process [or BiCMOS process] with a buried N-Well? The
body-drain diode should be included in the bsim4 model, but the body well
due to the buried n-well probably is not included in the model. I have not
looked at the diode models in the bsim4 model. Usually when a parasitic
device is included in a compact model, the model is somewhat simplified
to optimize simulator performance. Is it possible to use an external model
for the body diode? An external diode model may contain more parameters
and allow for more accurate simulation. Does your foundry provide data on
effects like saturation recovery? Is it possible that device self heating is an
issue? Is the body diode the only protection device or are you using an
external Schottky as the main protection device?
Best Regards,
Sheldon
Hi sheldon,
Thanks for the reply. It is helpful to us.
As I know, our foundy did not provide the effects like saturation recovery.
In addtion, we exclude the possiblity of the self heating to the performance. For the overcurrent protection, we have another block to handle it. I am not clear the function of the body diode or the external Schottky for protecting the overcurrent. The only adverse effect as I know is its EMI effecr for the saturation recovery of body diiode.
In present, we have found the VDD/GND bounce maybe the cause of the fault. We are still checking it.
Rhanks