[LTspice] Why does NMOS netlist with 4 nodes?

C

Chris Carlen

Guest
Hi:

The symbol nmos.asy included with LTspice only has 3 pins, yet this
symbol when included in a schematic netlists with 4 nodes.

Why is this?



Thanks.



--
_______________________________________________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
crcarleRemoveThis@BOGUSsandia.gov
NOTE, delete texts: "RemoveThis" and "BOGUS" from email address to reply.
 
Hello Chris,

The symbol nmos.asy included with LTspice only has 3 pins, yet this
symbol when included in a schematic netlists with 4 nodes.

Why is this?
Click to expand...
Substrate?

http://nina.ecse.rpi.edu/shur/remote/NMOS_extract.html

Regards, Joerg

http://www.analogconsultants.com
 
Joerg wrote:
Hello Chris,

The symbol nmos.asy included with LTspice only has 3 pins, yet this
symbol when included in a schematic netlists with 4 nodes.

Why is this?

Substrate?

http://nina.ecse.rpi.edu/shur/remote/NMOS_extract.html
Click to expand...

The M Spice primitive certainly has 4 terminals. But LTspice has both a
3-terminal and 4-terminal MOSFET symbol. The 3-terminal symbol netlists
4 nodes. I am simply curious as to how this occurs, since it is
inconsistent with the symbol's 3 terminals.


Good day!




--
_______________________________________________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
crcarleRemoveThis@BOGUSsandia.gov
NOTE, delete texts: "RemoveThis" and "BOGUS" from email address to reply.
 
On Wed, 08 Jun 2005 14:21:30 -0700, Chris Carlen
<crcarleRemoveThis@BOGUSsandia.gov> wrote:

Joerg wrote:
Hello Chris,

The symbol nmos.asy included with LTspice only has 3 pins, yet this
symbol when included in a schematic netlists with 4 nodes.

Why is this?

Substrate?

http://nina.ecse.rpi.edu/shur/remote/NMOS_extract.html


The M Spice primitive certainly has 4 terminals. But LTspice has both a
3-terminal and 4-terminal MOSFET symbol. The 3-terminal symbol netlists
4 nodes. I am simply curious as to how this occurs, since it is
inconsistent with the symbol's 3 terminals.


Good day!
Click to expand...
Netlists as

MN1 %d %g %s %s ModelName L=...

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
"Chris Carlen" <crcarleRemoveThis@BOGUSsandia.gov> schrieb im Newsbeitrag
news:d87e3i01erh@news4.newsguy.com...
Hi:

The symbol nmos.asy included with LTspice only has 3 pins, yet this symbol
when included in a schematic netlists with 4 nodes.

Why is this?



Thanks.
Click to expand...
Hello Chris,

This fourth pin is normally connected to the substrate of a
monolithic MOSFET.

LTspice automatically connects this 4th pin to the source in the
netlist even when only a 3-pin symbol is used for a MOSFET.
It's simply convenient to always have the same syntax in the netlist.

The 3-pin symbol is intended for VDMOS and other MOSFETs with 3 pins.

There is also a 4-pin MOSFET symbol in the components library
especially for monolithic MOSFETs.

Best regards,
Helmut
 
"Helmut Sennewald" <helmutsennewald@t-online.de> wrote in message
news:d87q35$vkr$04$1@news.t-online.com...
LTspice automatically connects this 4th pin to the source in the
netlist even when only a 3-pin symbol is used for a MOSFET.
It's simply convenient to always have the same syntax in the netlist.
Click to expand...
I notice that it only does that when the symbol is netlisted with an `M'
prefix; if I use an `X' prefix then it netlists with only three terminals,
which is exactly what is required to run most subcircuit FET models.

Jonathan
 
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