[comp.lsi] Berkeley Tools: Sim2spice

louis@irisa.UUCP (Louis Chevallier ) (03/22/88)

     I  have  2  problems  with  sim2spice.   Sim2spice is a
Berkeley tool  which  generates a  spice source  file from a
.sim file.  I did not succeed  in  having it  to produce the
area and perimeter parameters for the  transistors while the
necessary data seem available.

     I also would like to know how  I can  take into account
the width and length corrections on  the transistors channel
without modifying myself their L and W attributes within the
spice file.

	Thanks in advance.

aes@whuts.UUCP (STEVENS) (03/23/88)

> I did not succeed  in  having it  to produce the
> area and perimeter parameters for the  transistors while the
> necessary data seem available.

This is not a feature of sim2spice.  Sim2spice will estimate
these capacitances as ideal capacitances ("C" cards).  It gets
the values for these capacitances from the Magic tech file.

>      I also would like to know how  I can  take into account
> the width and length corrections on  the transistors channel
> without modifying myself their L and W attributes within the
> spice file.

You can correct the length in MOS2 and MOS3 by adjusting the
model parameter LD.  You can adjust the length and width in
MOS4 (BSIM) by changing DL and DW.

In my personal experience, I have found that sim2spice is a waste
of time for the following reasons:

1) As you mentioned above, it does not include areas and perimeters

2) It frequently causes transistors to be connected upsidedown,
   which if not corrected, will cause SPICE to crash

3) It does not make MAGIC subcells into SPICE subcircuits, and
   the resulting SPICE files are big and unruly.  You end up
   wasting a lot of time massaging the sim2spice-generated file,
   when you could write your own SPICE file which will probably
   converge a lot better.

--Andy Stevens
AT&T Bell Labs, Whippany NJ
aes@zeppo.att.com