Bipolar Junction Transistor

Bipolar Junction Transistor - EE2004 1 EE2004 Electronic...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: EE2004 1 EE2004 Electronic Devices (Part II) A/P Tan Leng Seow ([email protected]) Room: E4-05-45H, Tel: 6516 2563 Module website http://courses.nus.edu.sg/course/eletanls/ee2004/main.htm EE2004 2 BIPOLAR JUNCTION TRANSISTOR (Part I) 3 EE2004 Reading Assignment boxshadowdwn D A Neamen, Semiconductor Physics and Devices, Third Edition, McGraw-Hill (2003). pp. 367 – 377. EE2004 4 1.1 Introduction The Bipolar Junction Transistor (BJT) is a device comprising two pn junctions which are close enough to each other to interact. Simplified block diagram and circuit symbols of (a) npn and (b) pnp bipolar transistor 3 regions: emitter, base, collector. emitter, base, collector. emitter, base, collector. emitter, base, collector. 2 types: npn npn npn npn or pnp pnp pnp pnp 2 junctions: base base base base-emitter emitter emitter emitter , , , , base base base base-collector collector collector collector EE2004 5 Active device Passive device Type Type Type Type Many possible functions: current gain, current gain, current gain, current gain, voltage gain, voltage gain, voltage gain, voltage gain, signal signal signal signal-power gain power gain power gain power gain One basic function: Rectifying Rectifying Rectifying Rectifying characteristics characteristics characteristics characteristics No. of No. of No. of No. of Functions Functions Functions Functions Three (Emitter, Base, Collector Emitter, Base, Collector Emitter, Base, Collector Emitter, Base, Collector) Two No. of No. of No. of No. of Terminals Terminals Terminals Terminals Two (Base-emitter, base collector) One No. of No. of No. of No. of Junctions Junctions Junctions Junctions Bipolar Junction Transistor Bipolar Junction Transistor Bipolar Junction Transistor Bipolar Junction Transistor PN Junction PN Junction PN Junction PN Junction EE2004 6 Attractions of BJT: (2) High drive current / unit capacitance, hence, fast, used for rf communications. Common Emitter Current Gain, β = i C / i B Common Base Current Gain, α = i C /i E (1) High Current Gain 1 < + = = B C C E C i i i i i α C B E i i i + = hence, Typically 30 < g163 < 300 EE2004 7 boxshadowdwn All terminal connections required at the surface of the semiconductor. boxshadowdwn Buried n ++ layer required to minimise collector resistance. boxshadowdwn The BJT is not a symmetrical device, the doping of the emitter and the collector are different. boxshadowdwn There is a need to isolate between transistors on the substrate using p + regions. Cross-section of an Actual Integrated Circuit npn Bipolar Transistor EE2004 8 Consider a npn BJT, each region is uniformly doped, abrupt junction; doping concentrations of N DE =10 19 , N AB = 10 17 , N DC = 10 15 cm-3 , respectively in emitter, base & collector....
View Full Document

Page1 / 25

Bipolar Junction Transistor - EE2004 1 EE2004 Electronic...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online