Harmonic Balance Options Reference

Option

Default Value

Description

abstol

1e-12

Absolute error tolerance for currents for the nonlinear equation solver (Amp)

alpha

1e-12

Conductance in parallel with each branch (mho, equivalent to G_MIN)

auto_refine_solution

no

For power sweeps, yes=increase number of harmonics as power increases

beta

0.0

Conductance between each node and ground (mho, equivalent to G_SHUNT)

cmin

0.0

Capacitance between each node and ground (Farad)

cluster_tol

1e-2

Multitone frequencies within this tolerance are clustered to save memory (Hz)

continuation

source_stepping_last_tone

Continuation strategy

source_stepping_last_tone (solve low-voltage case for last tone in TONES list, then increase voltages until true circuit is solved.)

pseudo_transient (use additive transient term)

continuation.pseudo_transient.max_h

Used only when continuation=pseudo_transient is in effect

5e3

Initial value of internal pseudotransient variable

continuation.pseudo_transient.pt_reltol_scale

Used only when continuation=pseudo_transient is in effect

0.8

Relative tolerance of pseudotransient reltol to standard HB

continuation.pseudo_transient.step_reltol_scale

Used only when continuation=pseudo_transient is in effect

0.8

Relative tolerance of pseudotransient continuation to standard HB

initial_guess

dc for single-tone, fewer_tones for multi-tone

Source for initial guess at voltages and currents

dc (Run DC)

fewer_tones (iterative guesses)

fewer_tones_transient (iterative guesses starting with result of transient analysis)

file (read from HB file)

transient (Run transient analysis)

zero (Zero)

initial_guess.fewer_tones_transient.num_cycles

(Used only when fewer_tones_transient is selected for the initial_guess option.)

20

Number of cycles of 1st tone period to run initial transient analysis

initial_guess.fewer_tones_transient.tmax

(Used only when fewer_tones_transient is selected for the initial_guess option.)

None

Suggested maximum step size for transient analysis

initial_guess.fewer_tones_transient.tstop

(Used only when fewer_tones_transient is selected for the initial_guess option.)

None

Stop time for transient analysis

initial_guess.transient.num_cycles

(Used only when transient is selected for the initial_guess option.)

20

Number of cycles of 1st tone period to run initial transient analysis

initial_guess.transient.tmax

(Used only when transient is selected for the initial_guess option.)

None

Suggested maximum step size for transient analysis

initial_guess.transient.tstop

(Used only when transient is selected for the initial_guess option.)

None

Stop time for transient analysis

initial_guess_file

(Used only when file is selected for the initial_guess option.)

None

Pathname and filename of SDF-format file with HB results to use as initial guess

limiting_step

0.3

Maximum absolute voltage update allowed per iteration for the nonlinear equation solver

linearsolver_reltol

1e-2

Reltol for linear solver

linearsolver_restarts

1

Maximum linear solver restarts

limiting_step

0.3 for nonlinear circuits.

Very large (disabled) for linear circuits.

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

maxk

None

Maximum number of harmonics at each frequency

max_linearsolver_iterations

100

Maximum number of iterations for linear equation solver

max_newton_iterations

20

Maximum number of iterations for the nonlinear equation solver

memory_over_speed

0

0 = Run to maximize speed, memory use may be excessive

1 = Run to conserve memory

method

hb

hb=standard HB calculation. shooting=HB method for strongly nonlinear circuits

power_of_two_expansion

1 for single-tone, 0 for multi-tone

Expand MAXK to

preconditioner

0

Select preconditioner
(1=time_ frequency, 0=bdf)

read_state

None

Read initial state from the specified file

reltol

1e-3

Relative error tolerance for currents and voltages (dimensionless)

result_as_initial_guess

1

When set to 0, disables the use of the result from each step in a sweep as the initial guess for the next sweep step.

strongly_nonlinear

0

0=linear/mild, 1=strongly nonlinear/shooting

td_preconditioner

1

1=use td preconditioner.
Mainly for internal use.

tones

None

List of frequencies to analyze

trim_tol

0

Harmonics voltage tolerance. Harmonics less than trim_tol after the initial guess are pruned. 0=no pruning.
Mainly for internal use.

trtol

7

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

tstab

None

Initial stabilization time. Can be used to change the starting phase of the HB algorithm

vntol

1e-7

Absolute error tolerance for voltages for the nonlinear equation solver (Volt)

write_final_state

Write the final values of node voltages to specified file.

write_initial_state

Write the initial (DC) values of node voltages to specified file.

zero_freq_at_end

1

Return to DC at end of simulation. Only for single-tone HB