eldo_user

Examples
Example 21—Post-Layout Simulation using DSPF
.alter
.DSPF_INCLUDE FILE=./dspf_opamp_follower.dspf DEV=DSPF
+ LEVEL=C
The nominal run is the pre-layout reference. The first .alter statement above runs the same
simulation, but this time using post-layout information from the dspf_opamp_follower.dspf
DSPF file (extracted from the opamp GDSII layout with Mentor Calibre xRC). Specifying
DEV=DSPF means that we also use the Instance section of the .dspf file. The instance section
basically contains the intentional devices (the MOS devices in this case). As the LEVEL is set
to C, only the grounded capacitors are taken into account (more precisely, the compound
capacitors indicated with the *|NET statements in the .dspf file are included). In this example
there are 9 such capacitors. The output waveform V(OP) is slightly degraded (slower and less
stable) compared to the pre-layout reference.
.alter
.DSPF_INCLUDE FILE=./dspf_opamp_follower.dspf DEV=DSPF
+ LEVEL=RCC
+ RMINVAL=0.1 CCMINVAL=0.001f
In the second .alter statement the command is specified with a different filtering. As the LEVEL
is set to RCC, the full DPSF content is used (all resistors, coupling and grounded capacitors).
However we apply some clamping to the values of the resistors and coupling capacitors. All
resistors smaller than 0.1 Ohm are ignored (shorted), and all coupling capacitors smaller than
0.001fF are ignored. The output waveform V(OP) is marginally different compared to the
previous case.
Notice the notes that are generated relating to the replacement of nodes in the original netlist by
DSPF networks:
Note 70: Node X_OPAMP1.DIFFP has been replaced by a DSPF network.
Note 70: Node X_OPAMP1.DIFFN has been replaced by a DSPF network.
Note 70: Node X_OPAMP1.CURMIR has been replaced by a DSPF network.
Eldo® User's Manual, 15.3 1325