Electronics and Communication Engineering

Ec8252 Electronic devices-Part A Questions Unit2- Anna University- 2017 Regulation Ec8252 Electronic Devices  Unit-2   PART A Questions 1.       What is a transistor? What are the types? Transistor consists of two junctions formed by sandwiching either p type or n type semiconductor between a pair of opposite types. Two types - *NPN transistor *PNP transistor  2.       Define BJT? A bipolar junction transistor is a three terminal semiconductor device in which the operation depends on the interaction of both majority and minority carriers and hence the name bipolar.  3.       Give the hie and heo equations of BJT? h 11  = h ie  -  The input impedance of the transistor (corresponding to the emitter resistance re).Unit ohms Ώ. h 22 =h oe   -   The  output  impedance  of  transistor.  This  term  is  usually  specified  as admittance and has to be inverted to convert it to impedance. Units’ siemans S.  4.       Why is the transistor called a current controlled de