                            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 load line contains every possible operating point for the circuit. A line is defined by two points. To draw the load line you have to get. the saturation point and the cutoff point:

Saturation point: Tells you the maximum possible collector current for the circuit.

Calculate: Visualize a short between the collector and emitter.

VCE --- > 0 Cutoff point : Tells you the maximum possible collector emitter voltage for the circuit. Calculate: Visualize the transistor internally open between collector and emitter.

VCE -- > VCC

VCE (cut) = VCC

Ex: Draw the load line for the given circuit. Fig. 4-1: CE amplifier base biased Fig. 4-2: Output curve

Saturation point: Cutoff point:

VCE (cut) = VCC = 15V Fig. 4-3: Output curve with loadline

HO: Suppose the collector resistance (in Fig. 4-1) is increased to 6KΩ. What happens to the dc load line?

Solution: VCE (cut) = 15V    