monte carlo with control script and MOS parameter set containing AGAUSS parameter variations (like commercial parameter libraries)

examples/Monte_Carlo/MC_2_circ.sp

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+Circuit to perform Monte Carlo simulation in ngspice
+* 25 stage Ring-Osc. using inverters with BSIM3
+
+vin in out dc 0.5 pulse 0.5 0 0.1n 5n 1 1 1
+vdd dd 0 dc 3.3
+vss ss 0 dc 0
+ve  sub  0 dc 0
+vpe well 0 dc 3.3
+
+.subckt inv1 dd ss sub well in out
+mn1  out in  ss  sub  n1  w=2u l=0.35u as=3p ad=3p ps=4u pd=4u
+mp1  out in  dd  well p1  w=4u l=0.35u as=7p ad=7p ps=6u pd=6u
+.ends inv1
+
+.subckt inv5 dd ss sub well in out
+xinv1 dd ss sub well in 1 inv1
+xinv2 dd ss sub well 1  2 inv1
+xinv3 dd ss sub well 2  3 inv1
+xinv4 dd ss sub well 3  4 inv1
+xinv5 dd ss sub well 4 out inv1
+.ends inv5
+
+xinv1 dd ss sub well in out5 inv5
+xinv2 dd ss sub well out5 out10 inv5
+xinv3 dd ss sub well out10 out15 inv5
+xinv4 dd ss sub well out15 out20 inv5
+xinv5 dd ss sub well out20 out inv5
+xinv11 dd 0 sub well out buf inv1
+* output is buf
+cout  buf ss 0.2pF
+*
+.options noacct
+
+* The following model parameters are varying statistically:
+* vth0, u0, tox
+* see the AGAUSS function used to define the parameter
+* the deviation is 10%, just for example, not measured
+
+********************************************************************************
+.model n1 nmos
++level=8
++version=3.3.0
++tnom=27.0
++nch=2.498e+17  tox=AGAUSS(9e-09, 9e-09, 10)  xj=1.00000e-07
++lint=9.36e-8 wint=1.47e-7
++vth0=AGAUSS(.6322,.6322,10)    k1=.756  k2=-3.83e-2  k3=-2.612
++dvt0=2.812  dvt1=0.462  dvt2=-9.17e-2
++nlx=3.52291e-08  w0=1.163e-6
++k3b=2.233
++vsat=86301.58  ua=6.47e-9  ub=4.23e-18  uc=-4.706281e-11
++rdsw=650  u0=AGAUSS(388.3203,388.3203,10) wr=1
++a0=.3496967 ags=.1    b0=0.546    b1=1
++dwg=-6.0e-09 dwb=-3.56e-09 prwb=-.213
++keta=-3.605872e-02  a1=2.778747e-02  a2=.9
++voff=-6.735529e-02  nfactor=1.139926  cit=1.622527e-04
++cdsc=-2.147181e-05
++cdscb=0  dvt0w=0 dvt1w=0 dvt2w=0
++cdscd=0 prwg=0
++eta0=1.0281729e-02  etab=-5.042203e-03
++dsub=.31871233
++pclm=1.114846  pdiblc1=2.45357e-03  pdiblc2=6.406289e-03
++drout=.31871233  pscbe1=5000000  pscbe2=5e-09 pdiblcb=-.234
++pvag=0 delta=0.01
++wl=0 ww=-1.420242e-09 wwl=0
++wln=0 wwn=.2613948 ll=1.300902e-10
++lw=0 lwl=0 lln=.316394 lwn=0
++kt1=-.3  kt2=-.051
++at=22400
++ute=-1.48
++ua1=3.31e-10  ub1=2.61e-19 uc1=-3.42e-10
++kt1l=0 prt=764.3
++noimod=2
++af=1.075e+00              kf=9.670e-28               ef=1.056e+00
++noia=1.130e+20            noib=7.530e+04             noic=-8.950e-13
+**** PMOS ***
+.model p1 pmos
++level=8
++version=3.3.0
++tnom=27.0
++nch=3.533024e+17  tox=AGAUSS(9e-09,9e-09,10) xj=1.00000e-07
++lint=6.23e-8 wint=1.22e-7
++vth0=AGAUSS(-.6732829,-.6732829,10) k1=.8362093  k2=-8.606622e-02  k3=1.82
++dvt0=1.903801  dvt1=.5333922  dvt2=-.1862677
++nlx=1.28e-8  w0=2.1e-6
++k3b=-0.24 prwg=-0.001 prwb=-0.323
++vsat=103503.2  ua=1.39995e-09  ub=1.e-19  uc=-2.73e-11
++rdsw=460  u0=AGAUSS(138.7609,138.7609,10)
++a0=.4716551 ags=0.12
++keta=-1.871516e-03  a1=.3417965  a2=0.83
++voff=-.074182  nfactor=1.54389  cit=-1.015667e-03
++cdsc=8.937517e-04
++cdscb=1.45e-4  cdscd=1.04e-4
++dvt0w=0.232 dvt1w=4.5e6 dvt2w=-0.0023
++eta0=6.024776e-02  etab=-4.64593e-03
++dsub=.23222404
++pclm=.989  pdiblc1=2.07418e-02  pdiblc2=1.33813e-3
++drout=.3222404  pscbe1=118000  pscbe2=1e-09
++pvag=0
++kt1=-0.25  kt2=-0.032 prt=64.5
++at=33000
++ute=-1.5
++ua1=4.312e-9 ub1=6.65e-19  uc1=0
++kt1l=0
++noimod=2
++af=9.970e-01              kf=2.080e-29               ef=1.015e+00
++noia=1.480e+18            noib=3.320e+03             noic=1.770e-13
+.end
+
+.end

examples/Monte_Carlo/MC_2_control.sp

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+* Perform Monte Carlo simulation in ngspice
+* script for use with 25 stage Ring-Osc. BSIM3
+* circuit is in MC_2_circ.sp
+* edit 'set sourcepath' for your path to circuit file
+* start script by 'ngspice -o MC_2_control.log MC_2_control.sp'
+*
+.control
+  save buf                     $ we just need output vector buf, save memory by more than 10x
+  let mc_runs = 100            $ number of runs for monte carlo
+  let run = 1                  $ number of the actual run
+
+* Where to find the circuit netlist file MC_2_circ.sp
+  set sourcepath = ( D:\Spice_general\ngspice\examples\Monte_Carlo )
+
+* create file for frequency information
+  echo Monte Carlo, frequency of R.O. > MC_frequ.log
+
+* run the simulation loop
+  dowhile run <= mc_runs
+    * without the reset switch there is some strange drift
+    * towards lower and lower frequencies
+    reset
+    set run ="$&run"              $ create a variable from the vector
+    set rndseed = $run            $ set the rnd seed value to the loop index
+    source MC_2_circ.sp           $ load the circuit, including model data
+    tran 15p 200n 0
+    write mc_ring{$run}.out buf   $ write each sim output to its own rawfile
+    linearize buf                 $ lienarize buf to allow fft
+    fft buf                       $ run fft on vector buf
+    let buf2=db(mag(buf))
+    * find the frequency where buf has its maximum of the fft signal
+    meas sp fft_max MAX_AT buf2 from=0.1G to=0.7G
+    print fft_max >> MC_frequ.log $ print frequency to file
+    destroy all                   $ delete all output vectors
+    remcirc                       $ delete circuit
+    let run = run + 1             $ increase loop counter
+  end
+
+  quit
+
+.endc
+
+.end