1. PEN NO 150493111001 Ahir Darshan 150493111004 Harsora Ashish 150493111007 Mistry Ravi

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3. The BJT – Bipolar Junction Transistor  Note: It will be very helpful to go through the Analog Electronics Diodes Tutorial to get information on doping, n-type and p-type materials. The Two Types of BJT Transistors: npnpnp npn E B C pnp E B C Cross Section B C E Schematic Symbol B C E Collector doping is usually ~ 10 6Collector doping is usually ~ 10 6 Base doping is slightly higher ~ 10 7 – 10 8Base doping is slightly higher ~ 10 7 – 10 8 Emitter doping is much higher ~ 10 15Emitter doping is much higher ~ 10 15 SNPIT&RC Education BE(DEGREE) EC WINTER-2104

4. BJT Relationships - Equations B C E IEIEIEIE ICICICIC IBIBIBIB - + V BE V BC + - +- V CE B C E IEIEIEIE ICICICIC IBIBIBIB - + V EB V CB + - +- V EC npn I E = I B + I C V CE = -V BC + V BE pnp I E = I B + I C V EC = V EB - V CB Note: The equations seen above are for the transistor, not the circuit. SNPIT&RC Education BE(DEGREE) EC WINTER-2104

5. NPNPNP SNPIT&RC Education BE(DEGREE) EC WINTER-2104

6. Modes of Operation Most important mode of operationMost important mode of operation Central to amplifier operationCentral to amplifier operation The region where current curves are practically flatThe region where current curves are practically flatActive: Saturation: Barrier potential of the junctions cancel each other out causing a virtual shortBarrier potential of the junctions cancel each other out causing a virtual short Cutoff: Current reduced to zeroCurrent reduced to zero Ideal transistor behaves like an open switchIdeal transistor behaves like an open switch * Note: There is also a mode of operation called inverse active, but it is rarely used. SNPIT&RC Education BE(DEGREE) EC WINTER-2104

7. Forward bias the BEJReverse bias the CBJ SNPIT&RC Education BE(DEGREE) EC WINTER-2104

8. Plot I B as f(V BE, V CE ) As V CE increases, more V BE required to turn the BE on so that I B >0. Looks like a pn junction volt-ampere characteristic. SNPIT&RC Education BE(DEGREE) EC WINTER-2104

9. Plot I C as f(V CE, I B ) Cutoff region (off) both BE and BC reverse biased Active region BE Forward biased BC Reverse biased Saturation region (on) both BE and BC forward biased SNPIT&RC Education BE(DEGREE) EC WINTER-2104

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11. KCL >> I E = I C + I B β F = h FE = I C /I B I C = β F I B + I CEO I E = I B (1 + β F ) + I CEO I E = I B (1 + β F ) I E = I C (1 + 1/β F ) I E = I C (β F + 1)/β F SNPIT&RC Education BE(DEGREE) EC WINTER-2104

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14. V CC V CC /R C SNPIT&RC Education BE(DEGREE) EC WINTER-2104

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19. ECE 442 Power Electronics SNPIT&RC Education BE(DEGREE) EC WINTER-2104

20. Input voltage rises from 0 to V 1 Base current rises to I B1 Collector current begins to rise after the delay time, t d Collector current rises to steady-state value I CS This “rise time”, t r allows the Miller capacitance to charge to V 1 turn on time, t on = t d + t r SNPIT&RC Education BE(DEGREE) EC WINTER-2104

21. Input voltage changes from V 1 to –V 2 Base current changes to –I B2 Base current remains at –I B2 until the Miller capacitance discharges to zero, storage time, t s Base current falls to zero as Miller capacitance charges to –V 2, fall time, t f turn off time, t off = t s + t f SNPIT&RC Education BE(DEGREE) EC WINTER-2104

22. Charge storage in the Base Charge Profile during turn-off SNPIT&RC Education BE(DEGREE) EC WINTER-2104

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27. Thank You 27