physics-class-12-unit-14-chapter-07-bipolar-junction-transistor-basics-l-7-8-2kjxyevsy28

Bipolar Junction Transistor Basics

Biopolar Juntion Transistor(BJT)

Transfer + Resistor $\Rightarrow$ Transfer of current from a low resistance part to a high-resistance part

p-n junction in forward bias $\Rightarrow$ Low resistance

In reverse bias $\Rightarrow$ Large resistance

Bipolar Junction Transistor Basics

Doping

Emitter $\rightarrow$ High doping

Base $\rightarrow$ Lightly doped

Collector $\rightarrow$ Moderably doped

Base $\rightarrow$ Thin $\sim$ micrometers

Bipolar Junction Transistor Basics

Transistor

p-n junction

Emitter, one puts an arrow

Arrow should go from p-side to n-side

Emittter base junction forward bias

Common Emitter modes

Bipolar Junction Transistor Basics

Common Emitter

Common Emitter modes

Bipolar Junction Transistor Basics

Common Base

Common base mode

Bipolar Junction Transistor Basics

Working of a Transistor

Base in lightly doped

Emitter is heavily doped

Typically

$I_c \approx$ 0.95 to 0.98

$B_{dc} = \frac{I_c}{I_B} \sim$ 20 to 50

$B_{ac} = \frac{\Delta I_c}{\Delta I_B}$

Bipolar Junction Transistor Basics

Transistor

$I_c»I_b$

$I_c \lesssim I_E$

$B_{ac} \approx B{dc}$

$I_c \approx$ 0.95 to 0.98
…..

Bipolar Junction Transistor Basics

Transistor

$B_{dc} = \frac{I_c}{I_B} \sim$ 20 to 50

$B_{ac} = \frac{\Delta I_c}{\Delta I_B}$

$I_c»I_b$

$I_c \lesssim I_E$

$B_{ac} \approx B{dc}$

Bipolar Junction Transistor Basics

Common Base Emitter

Bipolar Junction Transistor Basics

Common Base Emitter

p-n Junction

I-V characterstics

Input characterstics: $I_B - V_{BE}$

Output characterstics: $I_c - V_0$

$V_0 - V_c$ (Transfer characterstics)

$V_{BE} = V_C$ (Output voltage)

$I_B$ = (Input current)

Thank you