Transistor Amplifier Circuits Unit 4 – Common Collector Circuit
Exercise 1 – Common Collector Circuit DC Operation
EXERCISE OBJECTIVE
When you have completed this exercise, you will be able to determine the dc operating
conditions of a common collector (CC) transistor circuit by using a typical CC circuit. You will
verify your results with a multimeter and with calculations.
DISCUSSION
- In common collector transistor circuits the collector terminal is common to both the input and
the output signals. - Since no collector resistor is present the collector voltage (VC) equals the dc power supply
voltage (VA). - Base voltage (VB) is calculated using the voltage divider equation.
- Emitter voltage (VE) is about 0.6 Vdc less than the base voltage when the transistor is
operating normally. - Ohm’s law is used to calculate the emitter current (IE).
- Collector current (IC) is the emitter current minus the base current.
- The dc load line passes through the saturation point, Q-point, and the cutoff point.
- Cutoff occurs when VCE is equal to the supply voltage and IC equals 0 mA.
- Saturation occurs when VCE equals 0 Vdc and the IC is at maximum value.