eldo_user

Eldo Control Language
Task Definition
.define_task opamp (n=10)
set vdd[]=1.65 open_lg[]=60
set vx=0 i=0 max_olg=60 i_max_olg=1 vdd_max=1.5 ovs=0
// for each value of VDD from 1.5V to 1.8V, find out the DC
// offset, then inject it into a .AC simulation that computes the
// open loop gain, and store this gain in open_lg[] vector
for (type=step, param=i, start=1, stop=n, step=1)
vdd[i] = 1.5 + (i-1) * (1.8-1.5) / (n-1)
simulation(
+ powersupply(pvdd = vdd[i]),
+ follower(),
+ vx = @vout_follower)
simulation(
+ powersupply(pvdd = vdd[i]),
+ ac_open_loop(vout_follower = vx),
+ open_lg[i] = @open_loop_gain)
endstep
// find out for which value of VDD the open loop gain is maximal
i_max_olg = open_lg.imin
max_olg = open_lg[i_max_olg]
for (i=open_lg.imin + 1; i max_olg)
i_max_olg = i
max_olg = open_lg[i]
endif
endfor
vdd_max = vdd[i_max_olg]
// finally run a single transient simulation for this value of
// VDD which maximizes the open loop gain and extract the
// overshoot :
simulation(
+ powersupply(pvdd = vdd_max),
+ transient(),
+ ovs=@overshoot)
fprint (stdout, \
"Max. open loop gain : %.5g for VDD = %.5g. Corresponding
overshoot is : %.5g\n",\
max_olg, vdd_max, ovs)
.end_define_task
See “Variables” on page 821, “Flow Control Statements” on page 835, “Defining and
Running Simulations” on page 841, and the fprint function for more information on the
concepts used in the example.
816
Eldo® User's Manual, 15.3