Table of Contents
Monte Carlo analysis
AMS 3.70
HIT-KIT 3.70; spectra
details: file:///opt/cds/designKits/ams_v3.70/www/hitkit/circuit_sim/montecarlo/mismatch.html
Models setting
To run MC simulations you must set Monte Carlo sections of elements models.
So run virtuoso analog design environment and click setup → model libraries. Next change in libraries (cmos53, res, cap, etc) name of section, from *tm to *mc. For example cmostm → cmosmc.
Run of simulation
After change the models, you run the simulation: tools → monte carlo
Gauss distibution requiere over 30 samples. So number of runs should be higher than 30. To see all results, change save data between runs checkbox on true.
Results
Results as characteristic family:
In setup outputs set data type on wave.
Results as histograms:
In setup outputs set data type on scalar.
AMS 4.00
HIT-KIT 4.00; spectra
Models setting
To run MC simulations you must set Monte Carlo sections of elements models.
ICFB → Hit-Kit Utilities → Simulation Utilities → Change Model Files → Set MC models
Run of simulation
Monte Carlo simulations are available in ADE XL. If cellview adexl doesn't exist: in schematic window click Launch → ADE XL In dialog box choose Create new view and click OK (if adexl cellview exists - simple open it).
In toolbar Run change single run… on Monte Carlo Sampling. In Simulation options (first button on right) set method (mismatch, process or all), specified number of iterations and finally mark Save Data to Allow Family Plots.
Finally run the simulations (green button on run toolbar).
Remark All simulations type (dc, ac, etc) and outputs are set on Data View in Tests branch.
Phase Margin, GBW and open loop gain
Due to lack of corelations between instances on test bench, it is not possible to check above parameters in the standard AC simulations on replica circuits.
The solution is to run MC on stb analysis and use following expressions to obtain histograms of DC open loop gain, phase margin and gain-bandwidth product:
- DC Open loop gain:
dB20(value(getData("loopGain" ?result "stb") 0)) - Phase Margin:
getData("/phaseMargin" ?result "stb_margin") - GainBandWidth:
getData("/phaseMarginFreq" ?result "stb_margin")
