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Equivalent Circuit


Name Description Unit Type Default
ID Diode ID Text SD1
*IS Reverse saturation current Current 1e-11 mA
*JSW Periphery reverse saturation current Current 0 mA
*MULT Scaling factor   1
*AFAC Junction area   1
*PJFAC Junction periphery   1
*RS Series resistance Resistance 0.001 ohm
*N Ideality factor   1
*TT Storage time Time 0 ns
*CJ0 Zero-voltage bottom junction capacitance Capacitance 0 pF
*CJP Zero-voltage periphery junction capacitance Capacitance 0 pF
*VJ Built-in voltage Voltage 0.8 V
*PHP Periphery built-in voltage Voltage 0.8 V
*M Grading coefficient   0.5
*MJSW Periphery junction grading coefficient   0.33
*FC Depletion capacitance linearization parameter   0.5
*FCS Periphery depletion capacitance linearization parameter   0.5
*BV Breakdown voltage Voltage 1e+06 V
*IBV Current at breakdown voltage Current 1 mA
*IKF Forward knee current Current 0 mA
*IKR Reverse knee current Current 0 mA
*EG Energy gap @ TNOM; default is Si    
*XTI Temp scaling coefficient; default is Si PN   3.0
*TEXT Temperature at which diode params were determined Temperature 25 DegC
*T Temperature Temperature 25 DegC
*KF Flicker noise coefficient   0
*AF Flicker noise exponent   1.0
*FFE Flicker noise frequency exponent   1.0
*KB Burst noise coefficient   0.0
*AB Burst noise exponent   1.0
*FB Burst noise cutoff frequency   1.0
*NFLAG Noise model   SPICE model
*DCAP Capacitance model selector   1
*TLEV I/V temperature model   0
*TLEVC Capacitance temperature model   0
*CTA Temperature coefficient for CJ0   0
*CTP Temperature coefficient for CJP   0
*GAP1 First bandgap correction factor   0.000702
*GAP2 Second bandgap correction factor   1108
*TCV Breakdown voltage temperature coefficient   0
*TM1 First-order temperature coefficient for M   0
*TM2 Second-order temperature coefficient for M   0
*TPB Temperature coefficient for VJ   0
*TPHP Temperature coefficient for PHP   0
*TRS Resistance temperature coefficient   0
*TTT1 First-order temperature coefficient for TT   0
*TTT2 Second-order temperature coefficient for TT   0
*COMPAT Compatibility selector: HPSICE   AWR
*IMAX Maximum device current Current 1e6 mA
*NS Ideality factor for periphery diode    
*RSW Sidewall series resistance Resistance  
*GLEAK Bottom junction leakage conductive S  
*GLEAKSW Sidewall junction leakage conductive S  

* indicates a secondary parameter

Implementation Details

SDIODE started as an implementation of the D-device level 1of SPICE2. It has progressively been enhanced to the point that it now includes most of HSPICE extensions to the original diode model. Accordingly, this model is mapped into HSPICE as a D-device with parameter LEVEL set to 1.

Two parameters, NFLAG and COMPAT, are unique to Microwave Office diode implementation. NFLAG's behavior is quite obvious and deserves no further comment. COMPAT, the compatibility selection flag, can take three different values: HSPICE, AWR and SPECTRE. The HSPICE and Spectre values are used to emulate the behavior of the D-device level 1 and diode model in HSPICE and Spectre, respectively. The AWR value supports NI AWR's implementation of the pn junction diode with parasitics.

I/V Characteristic

There are five operating regions, as follows:

Region A:

Region B: for

Region C: for

Region D: for

Region E: for


The equations are designed so that derivatives of the I/V characteristics are continuous at the boundaries.


The junction capacitance is modeled as in the PNDCAP element. See PNDCAP for the equations.


SDIODE noise comes from four uncorrelated sources: thermal (associated with the series resistance) shot, flicker and burst noise (associated with the junction). The thermal noise is described by a current source in parallel with the series resistance and with spectral density

The shot, flicker and burst noise are described as current sources in parallel with the junction and with spectral densities:

k is Boltzman's constant, T is the temperature, q is the electron charge, IDC is the DC component of junction current, and all spectral densities are expressed in A2/Hz.

NOTE: This model can be used as a Schottky-barrier diode model when TT, the transit time, is set to zero.


This element does not have an assigned layout cell. You can assign artwork cells to any element. See “Assigning Artwork Cells to Layout of Schematic Elements” for details.


[1] P. Antognetti and G. Massobrio, Semiconductor Device Modeling with SPICE, New York: McGraw-Hill, 1988.

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