Transient Analysis

[poojapangoria]

I have made a layout of 2k SRAM memory with its peripherals. This memory
when extracted without RC simulates fine in transient analysis.

But when extracted with RC, it does not do transient analysis and gives
the following log.

***********************************************
Transient Analysis `tran': time = (0 s -> 5 ns)
***********************************************
Trying `homotopy = gmin' for initial conditions.
Trying `homotopy = source' for initial conditions.


Notice from spectre during IC analysis, during transient analysis `tran'.
Gmin = 1 pS is large enough to noticeably affect the DC solution.
dV(I9.+1042124:int_d) = -27.4133 mV
Use `gmin_check' option to eliminate or expand this report.


Important parameter values:
start = 0 s
outputstart = 0 s
stop = 5 ns
step = 5 ps
maxstep = 100 ps
ic = all
skipdc = no
reltol = 1e-03
abstol(I) = 1 pA
abstol(V) = 1 uV
temp = 27 C
tnom = 27 C
tempeffects = all
errpreset = moderate
method = traponly
lteratio = 3.5
relref = sigglobal
cmin = 0 F
gmin = 1 pS
and it stops after that, saying the simulation successful.

What should i do, so that it does the transient analysis properly?

 

[hikom]

Hi,

as it is written in the simulation report, I think during the
topology-check a conductance is added (probably in parallel to a
pn-junction). But this conductance seems to affect the solution of
the DC-analysis (starting point for the transient simulation). maybe
you should set the gmin_check parameter to get detailed information.
Furthermore you should choose ohter stimuli (rise-time, vmax).

greetings,
hikom

 

[Gerry Vandevalk]

Question for you:
What do you mean "with RC" ?

Once you "extract" the physical parasitics as per the Fab's requirements,
you have created a network that is (potentially)
order(s) of magnitude larger than the "without" simulation. You must
understand what you are doing here.

I find it somewhat amazing that you have no problem simulating thee 2k sram
without parasitics.


"poojapangoria" <pooja@ee.iitb.ac.in> wrote in message
news:e86063d1c6a9a7948a44719bcb202b55@localhost.talkaboutcad.com...

I have made a layout of 2k SRAM memory with its peripherals. This memory
when extracted without RC simulates fine in transient analysis.

But when extracted with RC, it does not do transient analysis and gives
the following log.

***********************************************
Transient Analysis `tran': time = (0 s -> 5 ns)
***********************************************
Trying `homotopy = gmin' for initial conditions.
Trying `homotopy = source' for initial conditions.


Notice from spectre during IC analysis, during transient analysis `tran'.
Gmin = 1 pS is large enough to noticeably affect the DC solution.
dV(I9.+1042124:int_d) = -27.4133 mV
Use `gmin_check' option to eliminate or expand this report.


Important parameter values:
start = 0 s
outputstart = 0 s
stop = 5 ns
step = 5 ps
maxstep = 100 ps
ic = all
skipdc = no
reltol = 1e-03
abstol(I) = 1 pA
abstol(V) = 1 uV
temp = 27 C
tnom = 27 C
tempeffects = all
errpreset = moderate
method = traponly
lteratio = 3.5
relref = sigglobal
cmin = 0 F
gmin = 1 pS
and it stops after that, saying the simulation successful.

What should i do, so that it does the transient analysis properly?