can I use 5.5v input using 0.25micron process. I don't want to use the HV MOS.

[allennlowaton]

hello EDA fellows,

As stated in the title, can I used a 5.5V input using the LV MOS of the 0.25micron process?

thank you.

 

[jgk2004]

I think you could do this if your transistors do not see the full 5.5V input voltage, thus they would need to be in there own wells so you wouldn't break down the transistors. For example if you have diff pair with NMOS inputs you would have to have a triple well process to put those NMos transistors in there own wells. If I remember correctly atleast in 90nm Cmos the Nwell breakdown was around 11V so this would be ok... Check 0.25um for its limit. Then you would have to cascode your tail transistors so make sure they don't see more then there limit VDs so they don't break down...

Hope this helps,
Jgk

 

[allennlowaton]

in my design, I will use the lithium ion battery which has a range of 2.7volts - 5.5volts. As I read in the 0.25micron process, there's 2.5v (nch/pch)
and 5v(nch5/pch5). Am I also correct, that the HV process is not standard?

 

[erikl]

Am I also correct, that the HV process is not standard?

Of course not. For the HV option (at least) 2 more masks are needed.

 

[erikl]

in my design, I will use the lithium ion battery which has a range of 2.7volts - 5.5volts.
As I read in the 0.25micron process, there's 2.5v (nch/pch) and 5v(nch5/pch5).

A lithium ion battery should never go beyond 4.3V. So you could use the 5V option (even possible with 5.5V supply), or use an external LDO following the Li-ion-batt to provide 2.5V supply to your chip.

 

[allennlowaton]

thank you jgk2004 and erikl...

 

[dick_freebird]

If you can float the NMOS body then you can make a 5V
tolerant input buffer, but you have to be sure about imposed
gate ox voltages. In a cheapo P-substrate flow, you may be
out of luck.

 

[upvl]

Officially, I would say no. However, the foundries tend to be conservative about the break voltage of the transistors. In some specific applications (like power amplifier) , you could and sometimes have to use higher voltage drop on the transistors to achieve the speficications. No one without intensive experience in this process could tell you the exact break voltage. Also, higher Vds is more serious than higher Vgs.