Hello,

   I am facing a problem of overshoot ringing. I use 2.5 V IO transistors as the output stage, because of the parasitic inductors (estimated as 1 nH) at both VDD and VSS, the output signal starts overshoot and ringing a bit. This overshoot voltage (peak value is 3.8 V) is over the breakdowm voltage, I am afraid it will damage the transistor or reduce the life time. Does anybody have the experience on solving this overshoot problem?
   I know the overshoot in the step response of the RCL is fundamental problem (as shown here http://www.cvel.clemson.edu/emc/calculators/RLC_Calculator/index.html), I try to reduce it, or else I have to change the transistors to 3.3 V IO transistors (bad option).
   Any comments are highly appreciated.
   Thank you.

deba wrote on Jun 1^st, 2017, 3:19am:


Thank you for your reply. I forget to mention that I cannot add the resistor to lower the Q, it also lowers the efficiency.

You might try looking through Power Supply Noise Reduction and see if you find anything that helps.

-Ken