characterization, modeling, and design of esd protection circuits

A.5. OPTION Card 179
• DAMP is a number between 0 and 1.0 determining how quickly Tracer will converge
on an open-contact solution using voltage biasing. The closer DAMP is to 1.0, the
more quickly Tracer will converge, but there is also an increased chance of slower
convergence due to overshoot. Usually the user should not be concerned with the value
of DAMP. Default: 0.9.
• TRYCBC is used only if there is an open contact. Tracer will only attempt to use
zero-current biasing when the current of the control electrode is greater than TRYCBC.
Otherwise, voltage biasing is used. In most cases the user does not have to worry about
this parameter. Default: 1.0X10-17A/µm. • ANGLE1, ANGLE2, and ANGLE3 are critical angles (in degrees) affecting the
smoothness and step size of the trace. They are described in detail in [28]. If the difference
in slopes of the last two solution points is less than ANGLE1, the step size will be
increased for the next projected solution. If the difference is between ANGLE1 and
ANGLE2, the step size remains the same. If the difference is greater than ANGLE2,
the step size is reduced. ANGLE3 is the maximum difference allowed, unless overridden
by the MINDL parameter. ANGLE2 should always be greater than ANGLE1 and
less than ANGLE3. Defaults: ANGLE1 = 5 o , ANGLE2 = 10 o , ANGLE3 = 15 o .
• ITLIM is the maximum number of Newton loops for a given solution as specified in
the method card of the PISCES input deck. The user should make sure that the value of
ITLIM specified here is the same as that in the input deck. In certain cases, a PISCES
solution may be aborted in Tracer because the solution will not converge within the
given number of iterations. In some of these cases Tracer will try to redo the solution
with a doubled number of iterations. If ITLIM is specified on the OPTION card, such
attempts will be made. If there is no itlim statement or ITLIM=0, no attempts will be
made. It is recommended that ITLIM be set to a low value, around 10 or 15 (or at least
high enough to allow convergence of the initial solution). However, for GaAs devices a
larger ITLIM of 20 or 25 is recommended. Default: 0.
• MINCUR is the value of the control current, in A/µm, above which Tracer carefully
controls step size and guarantees a smooth trace. Below this current level, the program
simply takes voltage steps as large as possible, i.e., as long as numerical convergence
can be achieved, without regard for smoothness. If MINCUR is set to 0.0, Tracer will
not begin smoothness control until it is past the first sharp turn in the I-V curve. This
value should be used when the user is only interested in the rough location of a break in