1. Voltage and Current Sources Circuit Symbols
ECE 201 Circuit Theory I

2. “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
ECE 201 Circuit Theory I

3. “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

4. Voltage-Controlled Voltage Source VCVS
Vs is the “output” voltage
Vx is the “reference” voltage
u is the “multiplier”
Vs = uVx
ECE 201 Circuit Theory I

5. Current-Controlled Voltage Source CCVS
Vs is the “output” voltage
Ix is the “reference” current
p is the multiplier
Vs = pIx
ECE 201 Circuit Theory I

6. Voltage-Controlled Current Source VCCS
Is is the “output” current
Vx is the “reference” voltage
a is the multiplier
Is = aIx
ECE 201 Circuit Theory I

7. Current-Controlled Current Source CCCS
Is is the “output” current
Ix is the “reference” current
b is the multiplier
Is = bIx
ECE 201 Circuit Theory I

8. Common-Emitter Transistor Amplifier
ECE 201 Circuit Theory I

9. The transistor and its equivalent circuit
ECE 201 Circuit Theory I

10. Substituting the equivalent circuit for Q1
ECE 201 Circuit Theory I

11. Active and Passive Elements
Active element
a device capable of generating electrical energy
Voltage source
Current source
Power source
Batteries
Generators
a device that needs to be powered (biased)
transistor
Passive element
a device that absorbs electrical energy
Resistor
Capacitor
Inductor
motor
light bulb
heating element
ECE 201 Circuit Theory I