The general form of the instance of an independent voltage source is the following:

V<name> <node1(+)> <node2(-)> [[DC] <value>] [AC <magnitude> [phase]] [transient specification] [DISTOF1 [f1_magnitude [f1_phase]]] [DISTOF2 [f2_magnitude [f2_phase]]]

Voltage sources, in addition to being used for circuit excitation, are the 'ammeters' for SPICE, that is, zero valued voltage sources may be inserted into the circuit for the purpose of measuring current. They of course have no effect on circuit operation since they represent short-circuits.



Is the name of the source.

node1(+), node2(-)

Are the positive and negative nodes, respectively. Note that voltage sources need not be grounded. Positive current is assumed to flow from the positive node, through the source, to the negative node.

DC value

Is the DC and transient analysis value of the source. If the source value is zero both for dc and transient analyses, this value may be omitted. If the source value is time-invariant (e.g., a power supply), then the value may optionally be preceded by the letters DC.

AC magnitude, phase

The AC magnitude and phase. The AC phase value is in degrees. The source is set to this value in the AC analysis. If magnitude is omitted following the keyword AC, a value of unity is assumed. If phase is omitted, a value of zero is assumed. If the source is not an ac small-signal input, the keyword AC and the ac values are omitted.

Transient specification

Any independent source can be assigned a time-dependent value for transient analysis. If a source is assigned a time-dependent value, the time-zero value is used for DC analysis. There are five independent source functions: pulse, exponential, sinusoidal, piece-wise linear, and single-frequency FM. If parameters other than source values are omitted or set to zero, the default values are assumed.

Pulse waveform PULSE(V1 V2 TD TR TF PW PER PHASE)
Sinusoidal waveform SIN(VO VA FREQ TD THETA PHASE)
Frequency-modulated waveform SFFM(VO VA FC MDI FS PHASEC PHASES)
Exponential waveform EXP(V1 V2 TD1 TAU1 TD2 TAU2)
Piecewise linear waveform PWL(T1 V1 <T2 V2 <T3 V3 ...>>)
Function waveform FUNC(expression)


DISTOF1 and DISTOF2 are the keywords that specify that the independent source has distortion inputs at the frequencies F1 and F2 respectively (see the description of the .DISTO control line). The keywords may be followed by an optional magnitude and phase. The default values of the magnitude and phase are 1.0 and 0.0 respectively. The phase value is in degrees.


VCC 10 0 DC 6 
VIN 13 2 0.001 AC 1 SIN(0 1 1MEG)
VMEAS 12 9 
VCARRIER 1 0 DISTOF1 0.1 -90.0 

See also

Distortion Analysis
Independent current source
Voltage source instance parameters