The options in this section modify the behavior of the transient analysis integration routines. Delta refers to the internal timestep. TSTEP and TSTOP refer to the step and stop values entered with the .TRAN statement. The options are grouped into three categories: method, tolerance, and limit:
BYPASS 
ABSH 
RELH 
Stops the transient analysis when all TRIGTARG and FINDWHEN measure functions are calculated. This option can result in a substantial CPU time reduction. If the data file contains measure functions such as AVG, RMS, MIN, MAX, PP, ERR, ERR1,2,3, and PARAM, then AUTOSTOP is disabled. 

Sets the maximum value for the internal timestep Delta.StarHspice automatically sets the DELMAX value based on various factors, which are listed in Timestep Control for Accuracy. This means that the initial DELMAX value shown in the StarHspice output listing is generally not the value used for simulation. 

Allows the use of voltage limiting in transient analysis. Default = 1000. 

Sets the fraction of a timestep (TSTEP) that Delta (the internal timestep) is decreased for the first time point of a transient. Decreasing the FS value helps circuits that have timestep convergence difficulties. It also is used in the DVDT = 3 method to control the timestep. where DELMAX is specified and BKPT is related to the breakpoint of the source. TSTEP is set in the .TRAN statement. Default = 0.25. 

Sets the fraction of a timestep (TSTEP) by which Delta (the internal timestep) is decreased for an iteration set that does not converge. It is also used in DVDT = 2 and DVDT = 4 to control the timestep. Default = 0.25. 

Sets the minimum conductance allowed for in a transient analysis time sweep. Default = 1e12. 

Determines the maximum timestep in the timestep algorithms used for transient analysis simulations. IMAX sets an upper limit on the number of iterations allowed to obtain a convergent solution at a timepoint. If the number of iterations needed is greater than IMAX, the internal timestep Delta is decreased by a factor equal to the transient control option FT, and a new solution is calculated using the new timestep. IMAX also works in conjunction with the transient control option IMIN. ITL4 is the same as IMAX. Default = 8.0. 

Determines the timestep in the algorithms used for transient analysis siimulations. IMIN sets a lower limit on the number of iterations required to obtain convergence. If the number of iterations is less than IMIN, the internal timestep, Delta, is doubled. This option is useful for decreasing simulation times in circuits where the nodes are stable most of the time, such as digital circuits. If the number of iterations is greater than IMIN, the timestep is kept the same unless the option IMAX is exceeded (see IMAX). ITL3 is the same as IMIN. Default = 3.0. 

Determines the timestep in the algorithms used for transient analysis simulations. IMIN sets a lower limit on the number of iterations required to obtain convergence. If the number of iterations is less than IMIN, the internal timestep, Delta, is doubled. This option is useful for decreasing simulation times in circuits where the nodes are stable most of the time, such as digital circuits. If the number of iterations is greater than IMIN, the timestep is kept the same unless the option IMAX is exceeded (see IMAX). ITL3 is the same as IMIN. Default = 3.0. 

Determines the maximum timestep in the timestep algorithms used for transient analysis simulations. IMAX sets an upper limit on the number of iterations allowed to obtain a convergent solution at a timepoint. If the number of iterations needed is greater than IMAX, the internal timestep Delta is decreased by a factor equal to the transient control option FT, and a new solution is calculated using the new timestep. IMAX also works in conjunction with the transient control option IMIN. ITL4 is the same as IMAX. Default = 8.0. 

Sets the transient analysis total iteration limit. If a circuit uses more than ITL5 iterations, the program prints all results to that point. The default allows an infinite number of iterations. Default = 0.0. 

Sets the TSTEP multiplier, which determines the maximum value, DELMAX, that can be used for the internal timestep Delta: DELMAX = TSTEPxRMAX Default = 5 when dvdt = 4 and lvltim = 1, otherwise, default = 2. 

Sets the minimum value of Delta (internal timestep). An internal timestep smaller than RMINxTSTEP results in termination of the transient analysis with the error message "internal timestep too small". Delta is decreased by the amount set by the FT option if the circuit has not converged in IMAX iterations. Default = 1.0e9. 

Sets a lower limit for the voltages that are printed in the output listing. All voltages lower than VFLOOR are printed as 0. This only affects the output listing: the minimum voltage used in a simulation is set by VNTOL (ABSV). 
After linearization of the individual elements within a StarHspice input netlist file, the linear equations are constructed for the matrix. Usercontrolled variables affecting the construction and solution of the matrix equation include options PIVOT and GMIN. GMIN places a variable into the matrix that prevents the matrix becoming illconditioned.
Select the PIVOT option for a number of different pivoting methods to reduce simulation time and assist in both DC and transient convergence. Pivoting reduces the error resulting from elements in the matrix that are widely different in magnitude. The use of PIVOT results in a search of the matrix for the largest element value. This element value then is used as the pivot.
StarHspice Manual  Release 2001.2  June 2001