In this chapter, you will learn about: Transistor characteristics and parameters, the gain factors: DC Beta and DC alpha, relationship of DC Beta and DC alpha, early effect, maximum transistor ratings.
COMSATS Institute of Information Technology Virtual campus Islamabad Dr. Nasim Zafar Electronics 1 EEE 231 – BS Electrical Engineering Fall Semester – 2012 BJTTransistor Characteristics and Parameters: Lecture No: 15 Nasim Zafar References: Ø Microelectronic Circuits: Adel S. Sedra and Kenneth C. Smith. Ø Electronic Devices : Thomas L. Floyd ( Prentice Hall ). Ø Integrated Electronics: Jacob Millman and Christos Halkias (McGrawHill) Ø Electronic Devices and Circuit Theory: Robert Boylestad & Louis Nashelsky ( Prentice Hall ) Ø Introductory Electronic Devices and Circuits: Reference: Chapter 4 – Bipolar Junction Transistors: Figures are redrawn (with some modifications) from Electronic Devices By Thomas L. Floyd Nasim Zafar Bipolar Junction Transistors BJTsCircuits C B E Nasim Zafar Transistor Types: v MOS Metal Oxide Semiconductor v FET Field Effect Transistor v BJT Bipolar Junction Transistor Nasim Zafar ◄ Transistor Characteristics and Hybrid Parameters Nasim Zafar An Overview of Bipolar Transistors: Ø Ø While control in an FET is due to an electric field. Control in a bipolar transistor is generally considered to be due to an electric current – current into one terminal determines the current between two others – as with an FET, a bipolar transistor can be used as a ‘control device’ Nasim Zafar Transistor Characteristics: Ø Transistor Geometry Ø Carrier motion (mobility) Ø Collector “collection efficiency” (Alpha) Ø Asymmetry: Efficiency / Breakdown voltages Ø NPN transistors are normally better than PNP since electron mobility is better than hole mobility Nasim Zafar Transistor Biasing Configurations and Operation Modes: Nasim Zafar 10 Beta ( ) or Amplification Factor: Ø IC and IB are determined at a particular operating point, Qpoint (quiescent point). Ø Typical values of dc range from: 30