檢視 $useconstId 的原始碼

Since DDCC solver is solved by input bias, therefore it is hard to obtain the exactly desired current density.  $useconstId is a command for the program
to get a certain Id value by tuning the bias itself to reach the required gate current. However, it is very time consuming. 

 $useconstId
 Id_value V_trial_min V_trial_max Vd_step_min Precision


 The Ig_value is the current density of gate ( or Base). The unit is A/cm since it is 2D simulation.

 The simulation program need to set Vd = constant and Vd (VC) in a range. Vs (VE) can be treated as emitter. 
 The program will try in a Vd bias ranging from <math>   Vd-V_{trial,min}<Vg< Vg+V_{trial,max} </math> in a minimum Vd interval Vd_step_min.
 Once the current error is within   Precision

 For example 
 $Schottky     
 1.4
 $gatebias     
 0.9   0.9   0.01   
 $drainbias     
 0.5   5.0   0.5   
 $sourcebias     
 0.0
 $useconstId
 1.0e-3 -0.2 0.2 1.0e-4 1.0e-3