User`s guide

13
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30 Monte Carlo and Sensitivity/Worst-Case Analyses
maximized and Rb1 is minimized. Checking their individual
effects is not sufficient, even if the circuit were simulated four
times with each resistor in turn set to its extreme values.
* Worst-case analysis comparing monotonic and non-monotonic
* output with a variable parameter
.lib
***** Input signal and blocking capacitor *****
V
in In 0 ac 1
Cin In B 1u
***** "Amplifier" *****
* gain increases with small increase in Rb2, but
* device saturates if Rb2 is maximized.
V
cc Vcc 0 10
Rc Vcc C 1k
Q1 C B 0 Q2N2222
Rb1 Vcc B 10k
Rb2 B 0 Rbmod 720
.model Rbmod res(R=1 dev 5%) ; WC analysis results
; are correct
* .model Rbmod res(R=1.1 dev 5%) ; WC analysis misled
; by sensitivity
***** Load and blocking capacitor *****
CoutC Out 1u
Rl Out 0 1k
* Run with either the .STEP or the .WC, but not both.
* This circuit file is currently set up to run the .STEP
* (.WC is commented out)
**** Parametric Sweep—providing plot of Vm([OUT]) vs. Rb2 ****
.STEP Res Rbmod(R) 0.8 1.2 10m
***** Worst-case analysis *****
* run once for each of the .model definitions stated above)
* WC AC Vm([Out]) min range 99k 101k list output all
.AC Lin 3 90k 110k
.probe
.end
Fi
g
ure 13-14
Amplifier Netlist and Circuit File