Hi Rakesh,


the short answer is yes.

As I recall, if you have 1.2-V technology, then your oxide can sustain 1.2-V DC + about 10%, but you shouldn't use a supply voltage more than 1.2 V. You can look up the TDDB (time dependent dielectric breakdown) specs for the process, and you will see that the mean time to failure reduces exponentially with voltage. In your case, this time to failure can approximately be multiplied by the duty cycle. i.e. if you duty cycle is 20%, then the oxide will last 5x longer, but remember that as the time to failure reduces exponentially with voltage but only linearly with time, a 1/5 duty cycle has nowhere near the impact as 5x voltage.

Note that there are some papers which claim that at RF, transistors can sustain much larger AC swings. I don't recall which papers they are, and I don't think manufacturers normally check the transistors against large RF AC voltage swings, so try it at your own risk. IMO 4 V seems way too large for a 1.2-V transistor.

In your case, you can consider using the I/O transistors. Also, have a look at class-E PA papers to see what techniques they use to meet reliability requirements.


Aaron