Engineering Yield Calculator

Engineering Yield Calculator determines yield i.e. the percentage of variable space when a set of equations of the form -0.25 < f(a, b, c, d, e, f) < 0.71 are satisfied. The variables can have Gaussian or Uniform variation. You can use up to 25 variables (A-D,F-Z) and as many equations as you like. You can use dependent variables which are both random and have a dependency (which can range from -1.0 to +1.0) on the value of an independent variable. For example, in a field effect transistor the threshold voltage Vth variation can be made to be dependent on gate length variation. Then the variables and equations are sampled by the Monte Carlo method and the result displayed is yield % estimate of variable space when all the equations are simultaneously satisfied.

Supported operators are:

+

-

*

/

^ (power, e.g. 10^7)

% (modulo)

Supported functions are:

sin

cos

tan

asin

acos

atan

ln

log

exp

abs

sqrt

ceil

floor

Here is a sample input deck:

# lines starting with # are comments

# the first line has to say "yield calculator"

yield calculator

# the line starting with T tells the program the # of variables, # of equations, # of samples (max 75000), you can define up to 6 variables (2 dependent) and 3 equations

T, 4, 2, 75000

# variables come first, independent variable format is V, name (cannot be e,E), type G or U, mean, variation (3 sigma)

V, l, G, 3.2E-8, 6.0E-9

# dependent variables depend on the previous variable and the format is V, name, type G or U, mean, variation (3 sigma), dependence

V, t, G, 0.5, 0.05, 0.3

# t above is a dependent variable which depends on l

V, o, G, 1.0E-8, 3.0E-9

V, n, G, 0.06, 0.01

# Then come the equations, the format is E, minVal, equation, maxVal

#this may be a saturation current for a critical transistor at minimum length, such as in logic

E, 1.7E-5, (1.725e-11)*(n/o)*(6e-7/l)*(0.6-t)^2, 1.0E-4

#this may be a saturation current for a line buffer transistor at minimum length, such as in I/O

E, 1E-4, (8e-11)*(n/o)*(6e-7/l)*(0.6-t)^2, 5.0E-4

# you can add another equation for transconductance or gain of amplifier