                            Amplifier Teaching Aid (GTZ, DED; 86 pages)  Preface  Introduction  Lesson 1 - Semiconductor Review  Lesson 2 - Bipolar Transistor  Bipolar Transistor II  First Evaluation  Lesson 4 - Transistor Fundamentals   Lesson Plan    The load line    The operating point    Recognizing saturation    The transistor switch   Worksheet No. 4  Lesson 5 - Transistor Biasing  Lesson 6 - Transistor Biasing II  Second Evaluation  Lesson 7 - Small Signal Amplifier  Lesson 8 - Small Signal Amplifier II  Lesson 9 - Small Signal Amplifier III  Lesson 10 - Large Signal Amplifier  Third Evaluation

#### The operating point

Every transistor circuit has a load line. If the base resistance is given you can also calculate the current and voltage for the operating point.

Ex: Calculate the operating point (Q-point) Fig. 4-4: Base biased CE connection IC = βdc * IB = 100 * 29μA = 2.9 mA

VCE = VCC - (IC * RC) = 15V - (2.9 mA * 3KΩ) = 6.3V

By plotting IC (2.9 mA) and VCE (6.3V), we get the operation point ----> Q-point (quiescent point). Fig. 4 - 5: Collector curve with load line and Q - point

HO: Draw the load line and Q-point. Fig. 4-6: base biased CE connection, β=50

Solution: IC = IB * β = 2.15 mA

VCE = VCC - (RC * IC)= 5.7V VCE (cut) = VCC = 3.0V    