This chapter is the canonical supported-subset reference for Circuit elements, directives, models, validation behavior, and limitations.

Element Reference

This section lists the accepted element statements and their current syntax. Parsing support and analysis-domain support are distinct: frequency-dependent blocks are AC-only, while nonlinear devices and switches are intended for the transient solver.

Passive Elements

R - Resistor

Rname n+ n- value

Value in ohms. Positive, non-zero.

L - Inductor

Lname n+ n- value

Value in henries.

C - Capacitor

Cname n+ n- value

Value in farads.

K - Mutual Inductor Coupling

Kname L1 L2 coupling_coefficient

Coupling coefficient from -1 through 1. References two inductor instance names.

Independent Sources

V - Independent Voltage Source

Vname n+ n- [DC dc_value] [waveform]

I - Independent Current Source

Iname n+ n- [DC dc_value] [waveform]

Waveform functions: SIN, PULSE, PWL, EXP, SFFM, AM. Parameter order follows standard SPICE convention.

B - Behavioral Source

Bname n+ n- V=<supported waveform expression>
Bname n+ n- I=<supported waveform expression>

The current implementation accepts the supported source waveform functions; it is not a general SPICE expression evaluator.

Controlled Sources

E - VCVS (Voltage-Controlled Voltage Source)

Ename n+ n- nc+ nc- voltage_gain

G - VCCS (Voltage-Controlled Current Source)

Gname n+ n- nc+ nc- transconductance

F - CCCS (Current-Controlled Current Source)

Fname n+ n- vsource_name current_gain

H - CCVS (Current-Controlled Voltage Source)

Hname n+ n- vsource_name transresistance

Semiconductor Devices

D - Diode

Dname anode cathode [is=val] [n=val] [vt=val]

Shockley diode model with the listed positive inline parameters.

Q - BJT (Bipolar Junction Transistor)

Qname C B E [S] model_name [AREA area]

Gummel-Poon model. References a .model card of type NPN or PNP.

M - MOSFET

Mname D G S B model_name [W w] [L l] [M multiplier]

LEVEL=1 only (Shichman-Hodges, 1968). Unsupported LEVEL values: LEVEL 2 (Grove-Frohman), LEVEL 3 (semi-empirical), LEVEL 6 (MOS6), LEVEL 49 (BSIM3v3), LEVEL 54 (BSIM4). If you need BSIM accuracy, use an NPORT or S-parameter block to import foundry-characterized data.

Switches

S - Voltage-Controlled Switch

Sname n+ n- nc+ nc- model_name [ON|OFF]

.model type SW with RON, ROFF, VON, VOFF.

W - Current-Controlled Switch

Wname n+ n- vsource_name model_name [ON|OFF]

.model type CSW.

Frequency-Domain Elements

NPORT - Touchstone Import

NPORT name p1 n1 [p2 n2 ...] FILE=path [TYPE=Y|Z]

Supports Touchstone Y/Z datasets such as .ynp, .znp, .y2p, and .z2p. S datasets are not accepted by NPORT. AC analysis only.

S-Parameter Block

Sname nports p1 n1 [p2 n2 ...] FILE=path [Z0=value]

S-parameter block referencing a Touchstone .sNp or .ts file. This syntax is distinguished from a voltage-controlled switch because the second token is the positive port count and a Touchstone file token is present. AC analysis only.

Power-System Elements

XTAPZ - Tapped Series Impedance

XTAPZ name bus1 bus2 tap=value r=value x=value [phase=deg] [freq=hz]

tap, r, and x are required key/value options. tap and freq must be positive; phase defaults to zero and freq defaults to 60 Hz.

Subcircuits

.SUBCKT / .ENDS / X

.SUBCKT name node1 node2 ...
...
.ENDS
Xinstance node1 node2 ... subckt_name

Subcircuits are expanded (flattened) at parse time.

Directives Ignored with a Parse Warning

These SPICE directives are recognized but produce a parse warning:

.temp, .ic, .nodeset, .option, .options, .dc, .op, .tf, .meas, .measure, .plot, .func, .global, .if/.elseif/.else/.endif, .title, .csparam

Unsupported Elements

These produce a parse error with the element name for identification:

Kind	Name	Alternative
J	JFET	Use M (MOSFET) or controlled sources
T	Lossless transmission line	Use lumped RLC equivalents
O	Lossy transmission line	Use lumped RLC equivalents
U	Uniform RC line	Use discrete RC ladder
Z	MESFET (GaAs FET)	Use M (MOSFET)

NPORT transient analysis, MOSFET LEVEL > 1, and saturable magnetics are also unsupported.

Element Reference