eldo_user

Optimization
Specifying Design Variables
Specifying Design Variables
This topic uses examples to explain how to use the .PARAMOPT statement to specify design
variables. Design variables can be different types of circuit parameters and can take the
following forms:
parameter_name
P(parameter_name)
P(subckt_name, subckt_parameter)
E(device_name, device_parameter)
M(model_name, model_parameter)
EM(device_name, model_parameter)
In our first example, the length and width of a MOS transistor are specified by:
.PARAMOPT
+ L=(10U, 2U, 100U)
+ W=(60U, 2U, 200U)
This .PARAMOPT statement defines an initial length of 10μm and a initial width of 60μm. The
length is allowed to vary between 2μm and 100μm and the width can to take values between
2μm and 200μm.
Suppose an optimization is required on the following circuit:
.MODEL NMOD1.1 NMOS LEVEL=53
+ LMIN=0.1U LMAX=0.2U
+ WMIN=1U WMAX=100U
+ VTH0=0.2
.MODEL NMOD1.2 NMOS LEVEL=53
+ LMIN=0.2U LMAX=0.3U
+ WMIN=1U WMAX=100U
+ VTH0=0.3
.MODEL NMOD1.3 NMOS LEVEL=53
+ LMIN=0.3U LMAX=1U
+ WMIN=1U WMAX=100U
+ VTH0=0.4
VD D 0 DC 1.5
VS S 0 DC 0
VB B 0 DC 0
VG G 0 DC 3
RD1 D D1 1
RD2 D D2 1
M1 D2 G S B NMOD1 W=10U L=0.25U
M2 D1 G S B NMOD1 W=10U L=0.35U
Adding the following commands adjusts the length of M2:
.PARAMOPT E(M2,L)=(0.35U, 0.1U, 1U)
596
Eldo® User's Manual, 15.3