In the circuit of C E amplifier, a silicon transistor is used. The value of V CC = + 20 V , R L = 3 k Ω , collector voltage = 5 V , β = 100 . Then the base resistance R B should be (Take input voltage drop across Si transistor = 0.7 V )

Question

In the circuit of C E amplifier, a silicon transistor is used. The value of V CC = + 20 V , R L = 3 k Ω , collector voltage = 5 V , β = 100 . Then the base resistance R B should be (Take input voltage drop across Si transistor = 0.7 V ), 3 . 86 × 10 5 Ω, 2 . 16 × 10 4 Ω, 1 . 39 × 10 4 Ω, 5 . 44 × 10 5 Ω

MARKS App · Accepted Answer

V C C = V C + I C R L ∴ 20 = 5 + 3 × 10 3 I C ∴ I C = 15 3 × 10 3 = 5 × 10 - 3 A = 5 mA , β = I C I B ∴ I B = I C β = 5 × 10 - 3 100 = 5 × 10 - 5 A V C C = I B R B + P . D . across input junction As silicon transistor is in forward bias, the P . D . across input junction is 0 . 7 volt. ∴ 20 = 5 × 10 - 5 R B + 0.7 ∴ R B = 19.3 5 × 10 - 5 ∴ R B = 3.86 × 10 5 Ω

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