Maximum voltages on dc-dc converter switches (180nm CMOS)

[jkatic]

Hi,

I am designing a low power boost converter in 180nm CMOS. I am a beginner in the field, so any advice is welcome. I would like to drive my switches with maximum possible gate voltages in order to minimize their Ron (maximize efficiency) and to be safe at the same time. So, I am wondering how to determine this value? Which one of these should I follow:

1. Voltage should not exceed Vdd which is 1.8V.
2. In the PDK documentation, the BVN (for nmos) is 4.0V, but I am not sure what is this value.
3. Electrical field across gate oxide Eox=Vox/tox should be <1V/nm.
4. Vbox<12.6V warning from the tool when I sweep the gate voltage.

Thank you in advance.

 

[gelo]

Hi,

I am designing a low power boost converter in 180nm CMOS. I am a beginner in the field, so any advice is welcome. I would like to drive my switches with maximum possible gate voltages in order to minimize their Ron (maximize efficiency) and to be safe at the same time. So, I am wondering how to determine this value? Which one of these should I follow:

1. Voltage should not exceed Vdd which is 1.8V.
2. In the PDK documentation, the BVN (for nmos) is 4.0V, but I am not sure what is this value.
3. Electrical field across gate oxide Eox=Vox/tox should be <1V/nm.
4. Vbox<12.6V warning from the tool when I sweep the gate voltage.

Thank you in advance.

BVN is the breakdown voltage of the NMOS transistor.
If this voltage is exceeded, the transistor will either be partially damage or totally damged
BTW, what is your VIN operating range and expected VOUT voltage?

 

[jkatic]

Thank you for your answer. Number 3 gives the same result, since Tox=4nm. I will also leave some margin (at least 1Vth).

Vin is 0.1 to 0.5V and Vout 1.8V, it is for energy harvesting applications.