Transistor as an amplifier

A device which increases the amplitude of the input signal is called amplifier.

NPN transistor as CE amplifier

• i_e =i_b +i_c; i_b= 5% of i_e and i_c= 95% of i_e
• V_cc > V_BB
• Net collector voltage V_{CE =}v_cc-i_cR_L
• Input and output signals are 180° out of phase.

Transistor as CB amplifier

Transistor as CE amplifier

Relation between α and ß

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