Global Analysis Options Reference

Option

Default Value

Description

abstol

1e-9

Absolute error tolerance for currents (Amps)

alpha

0.0

Minimum conductance of the resistor placed in parallel with each branch (mho)

auto_select_solver

No

When Yes, Nexxim selects the sparse linear solver that will give the best performance for all simulations in the netlist

autoconverge

1

1 = Enable automatic cyclic progression through convergence methods upon convergence failure.

0 = Disable automatic cycling of methods.

behavioral_minimum_divisor

0

Minimum divisor to use for behavioral components in Nexsys simulations. Set to nonzero value to previent division by zero.

beta

0.0

Minimum conductance of the resistor placed between each node and ground (mho)

dcic

1

Flag to ignore initial conditions

delmax

None

Maximum timestep (Seconds)

gmax

1e2

Maximum conductance of the resistor placed in parallel with each branch (mho)

gmindc

0.0

Minimum conductance of the resistor placed in parallel with each branch (mho)

gshunt

0.0

Minimum conductance of the resistor placed between each node and ground (mho)

iabstol

1e-9

Absolute error tolerance for currents (Amps)

limiting

1

1=allow limiting on Newton steps

limiting_step

0.3 for nonlinear circuits.

Very large (disabled) for linear circuits.

Maximum absolute voltage update allowed per N-R iteration (Volts)

ltratio

7.0

Ratio of transient analysis tolerance to Newton-Raphson tolerance, for timestep calculation

max_continuation_iterations

500

Maximum number of continuation steps allowed per strategy

max_newton_iterations

10 (TRAN)
200 (DC)
20 (HB)

Maximum number of Newton-Raphson (N-R) iterations per continuation step

maxiters

10 (TRAN)

Maximum number of Newton-Raphson iterations for each timestep

maxstep

None

Maximum timestep (Seconds)

method

trap

Integration method (parentheses show synonyms for methods):

trap (trapezoidal)

gear (bdf2)

ndf2

minimum_divisor

0

Minimum divisor. Use 1e-28 for HSPICE compatibility.

num_threads

1

Number of independent processor threads to use during analyses

order_with_values

0

0=default sparse matrix solver

1=earlier solver, uses values in Jacobian in computing the fill reduction ordering

parhier

None

PARHIER=L reverses the precedence of parameter assignment in subcircuits

password

None

To access encrypted password-protected external files.

reltol

1e-3

Relative error tolerance for currents and voltages

result_as_initial_guess

1

1=Use of the result from each step in a sweep as the initial guess for the next sweep step.

rmax

10

Factor for calculating maximum timestep

seed

None

Used by random-value generator to initialize the sequence of pseudorandom values. Using the same seed generates the same sequence of values.

skip_dc

no

yes=Field solvers need not solve for DC. Use this option only for circuits with linear devices and no non-zero-valued sources except AC sources.

no=Solve for DC.

tmax

stoptime/100

Maximum step size

trtol

7.0

Ratio of transient analysis tolerance to Newton-Raphson tolerance, for timestep calculation

unit_atto

None

When set, A as a numeric suffix means e-18 (atto) rather than Ampere.

use_gpu

0

1=Use installed GPU to accelerate simulation and eye rendering for AMI, QE, and TRAN

vabstol

50e-6

Absolute error tolerance for voltages (Volts)

vntol

50e-6

Absolute error tolerance for voltages (Volts)