Resistors
Capacitors and Inductors
Coupled Mutual Inductors
Transmission Lines
Linear Dependant Sources
Independant Voltage and Current Sources
- PULSE Waveforms
- Sinusoidal Waveforms
- Exponential Waveforms
- Piecewise Linear Waveforms
- Single frequency FM Waveform
General form:
RXXXXXXX N1 N2 VALUE < TC=TC1< ,TC2 >
Examples:
R1 1 2 100 RC1 12 17 1K TC=0.001,0.015
N1 and N2 are the two element nodes. VALUE is the resistance (in ohms) and may be positive or negative but not zero.
TC1 and TC2 are the (optional) temperature coefficients; if not specified, zero is assumed for both. The value of the resistor as a function of temperature is given by:
value(TEMP) = value(TNOM)*(1+TC1*(TEMP-TNOM)+TC2*(TEMP-TNOM)**2))
General form:
CXXXXXXX N+ N- VALUE < IC=INCOND >
LYYYYYYY N+ N- VALUE < IC=INCOND >
Examples:
CBYP 13 0 1UF
COSC 17 23 10U IC=3V
LLINK 42 69 1UH
LSHUNT 23 51 10U IC=15.7MA
N+ and N- are the positive and negative element nodes, respectively. VALUE is the capacitance in Farads or the induc- tance in Henries.
For the capacitor, the (optional) initial condition is the initial (time-zero) value of capacitor voltage (in Volts). For the inductor, the (optional) initial condition is the initial (time-zero) value of inductor current (in Amps) that flows from N+, through the inductor, to N-. Note that the initial condi- tions (if any) apply 'only' if the UIC option is specified on the .TRAN card.
Nonlinear capacitors and inductors can be described.
General form :
CXXXXXXX N+ N- POLY C0 C1 C2 ... C0 C1 C2 ...(and L0 L1 L2 ...) are the coefficients of a
polynomial describing the element value. The capacitance is
expressed as a function of the voltage across the element while
the inductance is a function of the current through the inductor.
The value is computed as
value=C0+C1*V+C2*V**2+... where V is the voltage across the capacitor and I the
current flowing in the inductor.
General form:
KXXXXXXX LYYYYYYY LZZZZZZZ VALUE
Examples:
K43 LAA LBB 0.999
LYYYYYYY and LZZZZZZZ are the names of the two coupled
inductors, and VALUE is the coefficient of coupling, K, which
must be greater than 0 and less than or equal to 1. Using the
'dot' convention, place a 'dot' on the first node of each induc-
tor.
General form:
TXXXXXXX N1 N2 N3 N4 Z0=VALUE Examples:
T1 1 0 2 0 Z0=50 TD=10NS
N1 and N2 are the nodes at port 1; N3 and N4 are the nodes
at port 2. Z0 is the characteristic impedance. The length of
the line may be expressed in either of two forms. The
transmission delay, TD, may be specified directly (as TD=10ns, for example). Alternatively, a frequency F may be given, together with
NL, the normalized electrical length of the transmission line
with respect to the wavelength in the line at the frequency F.
If a frequency is specified but NL is omitted, 0.25 is assumed
(that is, the frequency is assumed to be the quarter-wave
frequency). Note that although both forms for expressing the line
length are indicated as optional, one of the two must be specified.
Note that this element models only one propagating mode. If
all four nodes are distinct in the actual circuit, then two modes
may be excited. To simulate such a situation, two transmission-
line elements are required. (see the example in Appendix A for
further clarification.)
The (optional) initial condition specification consists of
the voltage and current at each of the transmission line ports.
Note that the initial conditions (if any) apply 'only' if the UIC
option is specified on the .TRAN card.
One should be aware that SPICE will use a transient time-
step which does not exceed 1/2 the minimum transmission line
delay. Therefore very short transmission lines (compared with
the analysis time frame) will cause long run times.
SPICE allows circuits to contain linear dependent sources
characterized by any of the four equations
i=g*v
where g, e, f, and h are constants representing transconductance,
voltage gain, current gain, and transresistance, respectively.
Note: a more complete description of dependent sources as implemented in SPICE is given in Appendix B.
General form:
GXXXXXXX N+ N- NC+ NC- VALUE
Examples:
G1 2 0 5 0 0.1MMHO
N+ and N- are the positive and negative nodes, respectively.
Current flow is from the positive node, through the source, to
the negative node. NC+ and NC- are the positive and negative
controlling nodes, respectively. VALUE is the transconductance
(in mhos).
General form:
EXXXXXXX N+ N- NC+ NC- VALUE
Examples:
E1 2 3 14 1 2.0
N+ is the positive node, and N- is the negative node. NC+
and NC- are the positive and negative controlling nodes,
respectively. VALUE is the voltage gain.
General form:
FXXXXXXX N+ N- VNAM VALUE
Examples:
F1 13 5 VSENS 5
N+ and N- are the positive and negative nodes, respectively.
Current flow is from the positive node, through the source, to
the negative node. VNAM is the name of a voltage source through
which the controlling current flows. The direction of positive
controlling current flow is from the positive node, through the
source, to the negative node of VNAM. VALUE is the current gain.
General form:
HXXXXXXX N+ N- VNAM VALUE
Examples:
HX 5 17 VZ 0.5K
N+ and N- are the positive and negative nodes, respectively.
VNAM is the name of a voltage source through which the
controlling current flows. The direction of positive controlling current flow is from the positive node, through the source, to the negative node of VNAM. VALUE is the transresistance (in ohms).
A single pulse so specified is described by the following
table:
Intermediate points are determined by linear interpolation.
Syntax: SIN(VO VA FREQ TD THETA)
Examples:
VIN 3 0 SIN(0 1 100MEG 1NS 1E10)
The shape of the waveform is described by the following
table:
Syntax: EXP(V1 V2 TD1 TAU1 TD2 TAU2)
Examples:
VIN 3 0 EXP(-4 -1 2NS 30NS 60NS 40NS)
The shape of the waveform is described by the following
table:
Syntax: PWL(T1 V1 < T2 V2 T3 V3 T4 V4 ... >)
Examples:
VCLOCK 7 5 PWL(0 -7 10NS -7 11NS -3 17NS -3 18NS -7 50NS -7)
Parameters and default values
Each pair of values (Ti, Vi) specifies that the value of the source is Vi in Volts or Amps) at time=Ti. The value of the source at intermediate values of time is determined by using linear interpolation on the input values.
SFFM(VO VA FC MDI FS)
Examples: V1 12 0 SFFM(0 1M 20K 5 1K)
The shape of the waveform is described by the following
equation:
LYYYYYYY N+ N- POLY L0 L1 L2 ...
value=L0+L1*I+L2*I**2+...
KXFRMR L1 L2 0.87
v=e*v
i=f*i
v=h*i
Parameters Default Value Units
V1(initial voltage) Volts or Amps
V2(pulsed voltage) Volts or Amps
TD(delay time) 0.0 seconds
TR(rise time) TSTEP seconds
TF(fall time) TSTEP seconds
PW(Pulse Width) TSTOP seconds
PER(Period) TSTOP seconds
Time Value
0 V1
TD V1
TD+TR V2
TD+TR+PW V2
TD+TR+PW+TF V1
TSTOP V1
Parameter Default Value Units
V0(offset) 0 Volts/Amps
VA(amplitude) none Volts/Amps
FREQ(frequency) 1/TSTOP Hertz
TD(delay) 0 seconds
THETA(damping factor) 0 1/seconds
Time Value
0 to TD V0
TD to TSTOP V0+VA*EXP(-(TIME-TD)*THETA)*SINE(TWOPI*FREQ*(TIME+TD))
Parameter Default Value Units
V1(initial value) none Volts/Amps
V2(pulsed value) none Volts/Amps
TD1(rise delay time) 0 seconds
TAU1(rise time constant) TSTEP seconds
TD2(fall delay time) TD1+TSTEP seconds
TAU2(fall time constant) TSTEP seconds
Time Value
0 to TD1 V1
TD1 to TD2 V1+(V2-V1)*(1-exp(-(time-TD1)/TAU1))
TD2 to TSTOP V1+(V2-V1)*(1-(time-TD1)/TAU1))+(V1-V2)*(1-exp(-(time-TD2)/TAU2))
Parameter Stands for Default Value Units
V0 offset none Volts/Amps
VA amplitude none Volts/Amps
FC carrier frequency 1/TSTOP Hertz
MDI modulation index none
FS signal frequency 1/TSTOP Hertz