.BondLib.Spice.Utilities.CjD

Spice-style capacitor model for diodes

Information

The Spice-style junction capacitance for DIODEs computes the depletion and diffusion capacitance value of a junction used in a DIODE. Different Spice dialects vary in the formulae they use for this purpose. Many Spice dialects actually don't use a formula for the junction capacitance at all, but rather compute the electric charge stored in the junction directly, which is conceptually cleaner. However, that approach is computationally cumbersome, as it leads to an awkward algebraic loop [1]. Thus, we chose to compute the junction capacitance, and use a (physically incorrect) approximate non-linear capacitor model. The numerical error should remain small, as the time constants associated with temperature variation are much larger than those associated with electrical phenomena.

This particular model uses the capacitance formulae advocated in [2]. 

Parameters:

 Level:   DIODE modeling level (default value = 1)
            Level=1: Non-geometric junction diode
            Level=2: Fowler-Nordheim diode
            Level=3: Geometric junction diode

 Tnom:    Reference temperature (default value = 300.15 K)

 IS:      Saturation current at reference temperature (default value = 1e-14 Amp)

 N:       Current mission coefficient (default value = 1)

 TT:      Transit time at reference temperature (default value = 0 sec)

 CJ:      Zero-bias bulk capacitance at reference temperature (default value = 0.5e-12 F)

 PB:      Built-in junction potential at reference temperature (default value = 0.8 Volt)

 MJ:      Bulk junction grading coefficient (default value = 0.33)

 EG:      Energy gap for temperature effect on saturation current at 0 K (default value = 1.11 Volt)

 XTI:     Temperature exponent of saturation current (default value = 3)

 FC:      Forward-bias depletion capacitance coefficient (default value = 0.5)

 BV:      Reverse breakdown voltage at reference temperature (default value = 0 Volt)

 IBV:     Reverse breakdown current (default value = 0 Amp)

 TCV:     Linear temperature coefficient of breakdown voltage (default value = 0 V/K)

 TTT1:    Linear temperature coefficient of transit time (default value = 0 s/K)

 TTT2:    Quadratic temperature coefficient of transit time (default value = 0 s/K2)

 ISW:     Saturation current of perimeter at reference temperature (default value = 0 Amp)

 CJSW:    Zero-bias perimeter capacitance at reference temperature (default value = 0.5e-12 F)

 PHP:     Built-in perimeter potential at reference temperature (default value = 0.8 Volt)

 MJSW:    Perimeter capacitance grading coefficient (default value = 0.33)

 TOX:     Thin oxide thickness (default value = 1e-7 m)

 GminDC:  Leakage conductance (default value = 1e-16 mho)

 Area:    Relative area occupied by the diode (default value = 1)

 PJ:      Relative perimeter width (default value = 1)

 EMin:    if x < EMin, the exp(x) function is linearized (default value = -100)

 EMax:    if x > EMax, the exp(x) function is linearized (default value = 40)

 L:       Diode length (default value = 0 m)

 W:       Diode width (default value = 0 m)

 M:       Diode multiplier (default value = 1)

 JS:      Saturation current density at reference temperature (default value = 1e-4 Amp/m2)

 CJ2:     Zero-bias bulk capacitance per meter square at reference temperature (default value = 1e-4 F/m2)

 JSW:     Saturation current density of perimeter at reference temperature (default value = 0 Amp/m2)

 CJSW2:   Zero-bias perimeter capacitance per meter at reference temperature (default value = 1e-9 F/m)

 LP:       Polysilicon length (default value = 0 m)

 WP:       Polysilicon width (default value = 0 m)

 XP:       Widening of polysilicon due to masking and etching (default value = 0 m)

 XOI:      Polysilicon thickness (default value = 0 m)

 LM:       Metal length (default value = 0 m)

 WM:       Metal width (default value = 0 m)

 XM:       Widening of metal due to masking and etching (default value = 0 m)

 XOM:      Metal thickness (default value = 0 m)

 JF:       Forward Fowler-Nordheim current coefficient (default value = 0 A/V2)

 JR:       Reverse Fowler-Nordheim current coefficient (default value = 0 A/V2)

 EF:       Forward Fowler-Nordheim critical electrical field (default value = 0 V/m)

 ER:       Reverse Fowler-Nordheim critical electrical field (default value = 0 V/m)

References:

  1. Cellier, F.E. (1991), Continuous System Modeling, Springer-Verlag, New York, pp. 224-225.
  2. Massobrio, G. and P. Antognetti (1993), Semiconductor Device Modeling with Spice, 2nd edition, McGraw Hill, New York, p.200.
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