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ST JOSEPHS COLLEGE OF ENGINEERING SHOLINGANALLUR , CHENNAI 119 PE-1602 ADVANCED SEMICONDUCTOR DEVICES AND APPLICATIONS PART-A 1)Define field effect? 2)Why mosfets are intrinsically faster than bi-polar devices? 3)What are the charges that must be moved when the mosfets are turned on and off ? 4)Why power losses in mosfets are independent of junction temperature? 5)Why mosfets can be paralleled very easily? 6)What is parasitic BJT? 7)What are the factors that determine the safe operating area? 8)What are the advantages of proportional base control over constant drive circuit? 9)What happens if transistor is driven hard? 10)List the methods for isolating the control (or) gate signal with respect to ground ? PART-B 11(a) Discuss in detail about the devices used to limit the sureges to a tolerable level? (16) (or) (b)Discuss about any two types of overcurrent fault conditions. (16) 12)(a)With neat diagram explain the basic structure of a power mosfet? (16) (or) (b) Discuss about the voltage breakdown and on state conduction losses in a power mosfet? 13) (a) With neat diagram explain about the basic structure of IGBT. (or) (a) With relevant diagram discuss about the different techniques adopted for optimizing the base drive of a transistor. 14)(a)With relevant waveforms discuss about the turn on and turn off transients of IGBT? (16)

(or) (b)With relevant diagram explain how the isolation is implemented in thyristor firing circuits (16) 15)(a)Discuss in detail the structure of GTO and explain how it can be turned on and off? (or) (b) Discuss in detail the different reasons for over voltage in thyristor circuits