hSPICE and gm

Hello,

I recently wanted to find out what the gm of my transistors were when
doing simulations. Searching the web, I found that this parameter was
called LX7 and gds is LX8. Does anyone know how this came about? I
don't understand the how LX and a number are linked to a transistors
parameters.

 

[Steve]

On 31 Jul 2005 07:26:07 -0700, svinayag@gmail.com wrote:

I recently wanted to find out what the gm of my transistors were when
doing simulations. Searching the web, I found that this parameter was
called LX7 and gds is LX8. Does anyone know how this came about? I
don't understand the how LX and a number are linked to a transistors
parameters.

Hmmm. I thought they'd fixed this. Anyway, this comes from the SPICE2
basis of HSPICE. SPICE2 had a rather clever fortran memory manager
long before fortran could malloc memory. The memory was handled by
offsets from a base address, sort of like structures. The LX table
for each device was used to store derivatives and operating point
info. So, anyway, there is no real correlation between LX offsets and
the parameters stored there, other than that was how the LX table was
set up. But for user output, using the LX offsets for these instead
of names was very ugly.