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BJTs

• Physical structure and operation of the Bipolar Junction Transistor

• Current-voltage characteristics for BJTs

• Using BJTs in DC circuits

Overview

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BJTs

Physical Structure and Operation of BJTs

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BJTs

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BJTs

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BJTs

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BJTs

Cutoff

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BJTs

Active

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BJTs

Saturation

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BJTs

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BJTs

Consider an npn transistor with vBE = 0.7 V at iC = 1 mA. Find vBE at iC = 0.1 mA and 3 mA.

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BJTs

Transistors have β values in the range of 50 to 200. Find their α values.

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BJTs

Measurement of an npn BJT in a particular circuit shows the base current to be 14.46 μA, the emitter current to be 1.46 mA, and the base-emitter voltage to be 0.7 V. For these conditions, calculate α, β, and IS.

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BJTs

Calculate β for a transistors for which α = 0.99. For a collector current of 10 mA, find the base current of the transistor.

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BJTs

pnp BJT

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BJTs

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BJTs

Consider a pnp transistor whose base is grounded, the emitter is fed by a constant-current source that supplies a 2-mA current into the emitter terminal, and the collector is connected to a -10 V supply. Find the emitter voltage, the base current, and the collector current if for this transistor β = 50 and iS = 10-14

A.

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BJTs

Current Voltage Characteristics of BJTs

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BJTs

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BJTs

Consider the following circuit with β = 100 and vBE = 0.7 V at iC = 1 mA. Design the circuit to that a current of 2 mA flows through the collector and a voltage of +5 V appears at the collector.

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BJTs

Consider the following circuit with β = 100 and vBE = 0.7 V at iC = 1 mA. Design the circuit to that a current of 2 mA flows through the collector and a voltage of +5 V appears at the collector. REWORK assuming vBE = 0.7 V regardless of iC and β => ∞.

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BJTs

vBE = 0.7 V and β => ∞. Find all currents and voltages.

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BJTs

vBE = 0.7 V and β => ∞. Find all currents and voltages. Now assume base grounded.

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BJTs

Using a microcontroller to turn a red LED on and off.

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BJTs

Using a microcontroller to turn a red LED on and off.

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BJTs

Consider the following circuit with vBE = 0.7 V and β => ∞. Find all currents and voltages.

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BJTs

Consider the following circuit with vBE = 0.7 V and β = 50.

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BJTs

vBE = 0.7 V when on and β = 100. Find all currents and voltages.

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BJTs

vBE = 0.7 V when on and β = 100. Find all currents and voltages.

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BJTs

vBE = 0.7 V when on and β = 100. Find all currents and voltages. REWORK assuming vBE = 0.7 V regardless of iC and β => ∞.