D: Diode

Syntax

Dxxxxxxx n+ n- mname {area} {args}
.DIOde xxxxxxx n+ n- mname {area} {args}

Purpose

Junction diode.

Comments

N+ and n- are the positive and negative element nodes, respectively. Mname is the model name. Area is the area factor. If the area factor is omitted, a value of 1.0 is assumed. Args is a list of additional arguments. The parameters available are a superset of those available in SPICE.

A diode can also use a MOSFET model (type NMOS or PMOS) to represent the equivalent of the source-bulk or drain-bulk diodes.

When the element is printed out, by a list or save command, the the computed values of IS, RS, CJ, and CJSW are printed as a comment if they were not explicitly entered.

Element Parameters

Area = x

Area factor. (Default = 1.0) If optional parameters IS, RS, and CJO are not specified, the .model value is multiplied by area to get the actual value.

Perim = x

Perimeter factor. (Default = 1.0) If optional parameter CJSW is not specified, the .model value is multiplied by perim to get the actual value.

IC = x

Initial condition. The initial voltage to use in transient analysis, if the UIC option is specified. Default: don't use initial condition. This is presently ignored, but accepted for compatibility.

OFF

Start iterating with this diode off, in DC analysis.

IS = x

Saturation current. This overrides IS in the .model, and is not affected by area. Default: use IS from .model * area.

RS = x

Ohmic (series) resistance. This overrides RS in the .model, and is not affected by area. Default: use RS from .model * area. This is presently ignored, but accepted for compatibility.

CJ = x

Zero-bias junction capacitance. This overrides CJ in the .model, and is not affected by area. Default: use CJ from .model * area.

CJSW = x

Zero-bias sidewall capacitance. This overrides CJSW in the .model, and is not affected by perim. Default: use CJSW from .model * perim.

GParallel = x

Parallel conductance. This overrides GParallel in the .model, and is not affected by area. Default: use GParallel from .model * area.

Model Parameters

IS = x

Normalized saturation current. (Amperes). (Default = 1.0e-14) IS is multiplied by the area in the element statement to get the actual saturation current. It may be overridden by specifying IS in the element statement.

RS = x

Normalized ohmic resistance. (Ohms) (Default = 0.) RS is multiplied by the area in the element statement to get the actual ohmic resistance. It may be overridden by specifying RS in the element statement. RS is accepted, and silently ignored, for compatibility, but not implemented.

N = x

Emission coefficient. (Default = 1.0) In ECA-2 the default value was 2.

TT = x

Transit time. (Default = 0.) The diffusion capacitance is given by: $c_d = TT g_d$ where $g_d$ is the diode conductance.

VJ = x

Junction potential. (Default = 1.0) Used in computation of capacitance. For compatibility with older versions of SPICE, PB is accepted as an alias for VJ.

CJo = x

Normalized zero-bias depletion capacitance. (Default = 0.) CJo is multiplied by the area in the element statement to get the actual zero-bias capacitance. It may be overridden by specifying CJ in the element statement.

Mj = x

Grading coefficient. (Default = 0.5)

PBSw = x

Sidewall junction potential. (Default = PB)

CJSw = x

Normalized zero-bias sidewall capacitance. (Default = 0.) CJSw is multiplied by the perimeter in the element statement to get the actual zero-bias capacitance. It may be overridden by specifying CJSW in the element statement.

MJSw = x

Sidewall grading coefficient. (Default = 0.33)

EG = x

Activation energy. (electron Volts) (Default = 1.11, silicon.) For other types of diodes, use:

1.11 ev. Silicon (default value)
0.69 ev. Schottky barrier
0.67 ev. Germanium
1.43 ev. GaAs
2.26 ev. GaP

XTI = x

Saturation current temperature exponent. (Default = 3.0) For Schottky barrier, use 2.0.

KF = x

Flicker noise coefficient. (Default = 0.) SPICE parameter accepted but not implemented.

AF = x

Flicker noise exponent. (Default = 1.0) SPICE parameter accepted but not implemented.

FC = x

Coefficient for forward bias depletion capacitance formula. (Default = 0.5)

BV = x

Reverse breakdown voltage. (Default = $\infty$.) SPICE parameter accepted but not implemented.

IBV = x

Current at breakdown voltage. (Default = 1 ma.) SPICE parameter accepted but not implemented.

GParallel = x

Parallel conductance. (Default = 0.)

Probes

Vd

Voltage. The first node (anode) is assumed positive.

Id

Total current. It flows into the first node (anode), out of the second (cathode). I(Dxxxx) is the same as IJ(Dxxxx) + IC(Dxxxx).

IJ

Junction current. The current through the junction. IJ(Dxxxx) is the same as I(Yj.Dxxxx).

IC

Capacitor current. The current through the parallel capacitor. IC(Dxxxx) is the same as I(Cj.Dxxxx).

P

Power. P(Dxxxx) is the same as PJ(Dxxxx) + PC(Dxxxx).

PD

Power dissipated. The power dissipated as heat. It is always positive and does not include power sourced. It should be the same as P because the diode is passive.

PS

Power sourced. The power sourced by the part. It is always positive and does not consider its own dissipation. It should be 0 because the diode is passive.

PJ

Junction power. PJ(Dxxxx) is the same as P(Yj.Dxxxx).

PC

Capacitor power. PC(Dxxxx) is the same as P(Cj.Dxxxx).

Capacitance

Effective capacitance. C(Dxxxx) is the same as Capacitance(Cj.Dxxxx).

Req

Effective resistance. R(Dxxxx) is the same as R(Yj.Dxxxx).

Z

Impedance at a port. The port impedance seen looking into the circuit across the branch. It does not include the part itself. In transient analysis, it shows the effective Z-domain impedance, which is a meaningless number if there are capacitors or inductors in the circuit. (DC only)

ZRAW

Impedance at a port, raw. This is the same as ``Z'' except that it includes the part itself. (DC only)

REgion

Region code. A numeric code that represents the region it is operating in. +1 = forward, -1 = reversed, 0 = unknown, -2 = assumed off.

All parameters of the internal elements Yj and Cj are available. To access them, concatenate the labels for the internal element with the diode, separated by a dot. Yj.D6 is the admittance (Yj) element of the diode D6.

In this release, there are no probes available in AC analysis except for the internal elements.

The general element probes do not apply to diodes.