Download Voltage-Controlled Voltage Source VCVS

Voltage and Current Sources
Circuit Symbols
Vbattery
12 V
Isource
1A
ECE 201 Circuit Theory I
1
“IDEAL” or “Independent” Sources
• IDEAL voltage source
– maintains the
prescribed voltage
across its terminals
regardless of the
current drawn from it
• IDEAL current source
– maintains the
prescribed current
through its terminals
regardless of the
voltage across those
terminals
LOADCurrent
+
0.012
A
LOAD
Is
1A
+
LOADVoltage
999.001 V DC 1MOhm
Z=A+jB
Vs
12 V
Z=A+jB
DC 1e-009Ohm
LOAD
-
ECE 201 Circuit Theory I
2
“Controlled” or “Dependent” Sources
• A voltage or current source whose value
“depends” on the value of voltage or current
elsewhere in the circuit
• Use a diamond-shaped symbol
ECE 201 Circuit Theory I
3
Voltage-Controlled Voltage Source VCVS
+
Vx
-
+
Vs
1 V/V
Vs=uVx
-
• Vs is the “output”
voltage
• Vx is the “reference”
voltage
• u is the “multiplier”
• Vs = uVx
ECE 201 Circuit Theory I
4
Current-Controlled Voltage Source CCVS
+
Ix
Vs
1 Ohm
Vs=pIx
-
• Vs is the “output”
voltage
• Ix is the “reference”
current
• p is the multiplier
• Vs = pIx
ECE 201 Circuit Theory I
5
Voltage-Controlled Current Source VCCS
+
Vx
-
Is
1 Mho
Is = aVx
• Is is the “output”
current
• Vx is the “reference”
voltage
• a is the multiplier
• Is = aIx
ECE 201 Circuit Theory I
6
Current-Controlled Current Source CCCS
Ix
Is
1 A/A
Is=bIx
• Is is the “output”
current
• Ix is the “reference”
current
• b is the multiplier
• Is = bIx
ECE 201 Circuit Theory I
7
Common-Emitter Transistor Amplifier
VCC
12V
Rcollector
3.3kOhm
R2
47kOhm
Cc2
COLLECTOR
Cc1
BASE
Q1
2N2222A
1uF
EMITTER
V1
1V
1kHz
0Deg
1uF
R1
1kOhm
Rem itter
560 Ohm
ECE 201 Circuit Theory I
Rload
1kOhm
Ce
1uF
8
The transistor and its equivalent circuit
rbe
1kOhm
BASE
COLLECTOR
COLLECTOR
BASE
I1
1 A/A
Q
2N2222A
EMITTER
EMITTER
ECE 201 Circuit Theory I
9
Substituting the equivalent circuit for Q1
VCC
12V
R2
47kOhm
Rcollector
3.3kOhm
rbe
1kOhm
BASE
Cc1
ib --->
COLLECTOR
Cc2
1uF
BETAib
50 A/A
1uF
Rload
1kOhm
V1
1V
1kHz
0Deg
R1
1kOhm
EMITTER
Rem itter
560 Ohm
ECE 201 Circuit Theory I
Ce
1uF
10
Active and Passive Elements
• Active element
• Passive element
– a device capable of
generating electrical
energy
– a device that absorbs
electrical energy
• Voltage source
• Current source
• Power source
– Batteries
– Generators
– a device that needs to
be powered (biased)
•
•
•
•
•
•
Resistor
Capacitor
Inductor
motor
light bulb
heating element
• transistor
ECE 201 Circuit Theory I
11