EEE Dept Engineering Topics List

Bipolar Junction Transistors (BJT) | Electron Devices and Circuits

Subject and UNIT: Electron Devices and Circuits: Unit II: (a) Bipolar Junction Transistors (BJT)

Electron Devices and Circuits: Unit II: (a) Bipolar Junction Transistors (BJT) : University Questions with Answers (Long Answered Questions)

Bipolar Junction Transistors (BJT) | Electron Devices and Circuits

Subject and UNIT: Electron Devices and Circuits: Unit II: (a) Bipolar Junction Transistors (BJT)

Electron Devices and Circuits: Unit II: (a) Bipolar Junction Transistors (BJT) : Two Marks Questions with Answers

Bipolar Junction Transistors (BJT)

Subject and UNIT: Electron Devices and Circuits: Unit II: (a) Bipolar Junction Transistors (BJT)

• Transistors are widely used in digital logic circuits and switching applications. In these applications, the voltage levels periodically alternate between a "Low" and a "High" voltage, such as 0 V and + 5 V.

Bipolar Junction Transistors (BJT)

Subject and UNIT: Electron Devices and Circuits: Unit II: (a) Bipolar Junction Transistors (BJT)

• As mentioned earlier, compensation techniques use temperature sensitive devices such as diodes, transistors, thermistors, etc. to maintain operating point constant.

Bipolar Junction Transistors (BJT)

Subject and UNIT: Electron Devices and Circuits: Unit II: (a) Bipolar Junction Transistors (BJT)

• The different biasing circuits are : • Fixed bias circuit • Collector to base bias circuit • Voltage divider / self bias circuit • Emitter stabilized bias circuit • Miscellaneous bias circuit

Bipolar Junction Transistors (BJT)

Subject and UNIT: Electron Devices and Circuits: Unit II: (a) Bipolar Junction Transistors (BJT)

• We know that, the IC is a Unction of ICO, VBE and P Thus, it is convenient to introduce the three partial derivatives of IC with respect to these variables. These derivates are called stability factors S, S' and S" and are defined as follows :

Bipolar Junction Transistors (BJT)

Subject and UNIT: Electron Devices and Circuits: Unit II: (a) Bipolar Junction Transistors (BJT)

• Ideally, the Q point should be stable; it should not shift up and down on the dc load line. However, it is quite unstable.

Bipolar Junction Transistors

Subject and UNIT: Electron Devices and Circuits: Unit II: (a) Bipolar Junction Transistors (BJT)

• The transistor can be operated in three regions : cut-off, active and saturation by applying proper biasing conditions as shown in the Table 2.5.1.

Bipolar Junction Transistors (BJT)

Subject and UNIT: Electron Devices and Circuits: Unit II: (a) Bipolar Junction Transistors (BJT)

• The transistor can be connected in a circuit in the following three configurations. 1. Common base configuration. 2. Common emitter configuration. 3. Common collector configuration.

Bipolar Junction Transistors (BJT)

Subject and UNIT: Electron Devices and Circuits: Unit II: (a) Bipolar Junction Transistors (BJT)

• An unbiased transistor means a transistor with no external voltage (biasing) is applied. Obviously, there will be no current flowing from any of the transistor leads.

Bipolar Junction Transistors (BJT)

Subject and UNIT: Electron Devices and Circuits: Unit II: (a) Bipolar Junction Transistors (BJT)

• The middle region of each transistor type is called the base of the transistor. This region is very thin and lightly doped.

Subject and UNIT: Electron Devices and Circuits: Unit II: (a) Bipolar Junction Transistors (BJT)

• Transistor is a three terminal device : Base, emitter and collector, can be operated in three configurations common base, common emitter and common collector.