Notational Conventions
DC Quantity — Upper caseletter, uppercase subscript
V
BE
,
I
D
SmallSignal Quantity — Lower caseletter, lowercase subscript
v
be
,
i
d
Total Quantity — Lower caseletter, uppercase subscript
v
BE
=
V
BE
+
v
be
,
i
D
=
I
D
+
i
d
Phasor Quantity — Upper caseletter, lowercase subscript
V
be
,
I
d
Independent Sources
Figure 1(a) shows the diagram of an independent voltage source. The voltage
v
is independent of the current
i
that flows through the source. Fig. 1(b) shows the diagram of an independent current source. The current
i
is independent of the voltage
v
across the source.
Figure 1: (a) Independent voltage source. (b) Independent current source.
Dependent Sources
VCVS — Voltage Controlled Voltage Source
Figure 2(a) shows the diagram of a voltage controlled voltage source. The output voltage is given by a
voltage gain
A
v
multiplied by an input voltage
v
1
. Such a source in SPICE is called an E source.
Figure 2: (a) Voltage controlled voltage source. (b) Voltage controlled current source. (c) Current controlled
voltage source. (d) Current controlled current source.
VCCS — Voltage Controlled Current Source
Figure 2(b) shows the diagram of a voltage controlled current source. The output current is given by a
transconductance
G
m
multiplied by an input voltage
v
1
. Such a source in SPICE is called a G source.
CCVS — Current Controlled Voltage Source
Figure 2(c) shows the diagram of a current controlled voltage source. The output voltage is given by a
transresistance
R
m
multiplied by an input current
i
1
. Such a source in SPICE is called an F source.
CCCS — Current Controlled Current Source
Figure 2(d) shows the diagram of a current controlled current source. The output current is given by a
current gain
A
i
multiplied by an input current
i
1
. Such a source in SPICE is called an H source.
1
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Passive Elements
Resistor
Figure 3(a) shows the diagram of a resistor. The voltage across it is given by
v
=
iR
This relation is known as Ohm’s law.
Figure 3: (a) Resistor. (b) Inductor. (c) Capacitor.
Inductor
Fig. 3(b) shows an inductor. The voltage across it is given by
v
=
L
di
dt
In the analysis of circuits having sinusoidal excitations, phasor analysis is usually used. In this case, the
voltage across the inductor is given by
V
=
LsI
where
V
and
I
are phasors,
s
=
jω
, and
ω
is the radian frequency of the excitation. In the phasor domain,
a multiplication by
s
is equivalent to a time derivative in the time domain. This is because the time domain
excitation is assumed to be of the form
exp(
st
)
.
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 Summer '08
 HOLLIS
 Electrical impedance, Thévenin's theorem, Voltage source, Current Source, gm r1 r2

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