Monte Carlo

I have five transistors that reference the same model statement. The BF parameter in the model statement has a LOT tolerance specified. The LOT should provide absolute tracking, but the five transistors are not tracking each other at all during a Monte Carlo analysis.

The LOT tolerance does provide absolute tracking when multiple components reference the same model statement. However, if you go to Global Settings under the Options menu, the PRIVATEANALOG option will be enabled. This option forces all analog components to have their own model statement, thus nullifying LOT's absolute tracking effect. To have absolute tracking, PRIVATEANALOG must be disabled.

You can also use the lot# value which specifies one of 100 random number generators, numbered 0 through 99, that are used to calculate parameter values. The lot# lets you correlate parameters. Parameters that share the same lot# will track. If you change the LOT statement on your BF parameter to:

LOT/1=10%

the BF values would then track for all transistors that reference the model statement. This would be true even if PRIVATEANALOG was enabled.