Classification of Bipolar Transistor

The transistors with reference to power limit emerging from the collector junction, are divided into low power (up to 0.3W), medium power (0.3 – 1.5W), and high power (more than 1.5W). With reference to limiting frequency transistors are divided into low-frequency (up to 3mHr), medium frequency (3 – 30mHr) and high frequency (more than 30mHr) ones. There are two types of BT: drift transistors and diffusion ones. In the drift transistors transfer of minority charge carriers across the base take place due to drift under the action of an electric field. In the diffusion transistors the same transfer is provided mainly by means of diffusion.

Special system is used for BT marking. The first symbol of the system (digit/ letter) displays the type of a semiconductor: 1 or Г – germanium, 2 or K – silicon. The second symbol is letter T for all BT. The third symbol (three-digit number) displays power and frequency characteristics of a BT. The fourth one (letter) indicates the sort of the given transistor. For example – ГТ905A – germanium, high-power, high-frequency, sort A.

Test questions

1. Draw structural diagram of a bipolar transistor and explain how it operates.

2. What kind of voltage polarity is it necessary to apply to the n-p-n type BT to provide its active and saturation operation modes?

3. How does a BT realize the relay rule?

4. What methods are used for the BT circuits research?

5. When can a BT be considered as a linear component?

6. When is the grapho-analytic method used for the BT circuits research?

7. How does the slope of a load line change with R_ed changes?

8. What are the physical processes lead to decreasing β?

9. Draw three circuit connection diagrams of BT. Compare advantages and disadvantages of these circuits.

10. What process affects on BT quick-action?