A common base amplifier has an input resistance of 20 ohms and an output resistance of 100 kilo-ohms. If the alpha current gain is 0.98, what is the power gain of the amplifier?

A. 4900 — Power gain is the product of voltage gain and current gain. Voltage gain is alpha times the ratio of output resistance to input resistance, so power gain is alpha squared times the resistance ratio.

JEE Main · PhysicsHard

$A common base amplifier has an input resistance R_{i} = 20 Ω and an output resistance R_{o} = 100 k Ω . If the current gain α = 0.98, what is the power gain A_{p} of the amplifier?$

A. $4900$
B. $9800$
C. $2450$
D. $1960$

Show correct answer & step-by-step solution

Correct answer: A — $4900$

Solution

Power gain A_{p} = A_{v} \times α = (α \times \frac{R _{o}}{R _{i}}) \times α = α^{2} \times \frac{R _{o}}{R _{i}} . Substituting values: A_{p} = (0.98)^{2} \times \frac{100000}{20} = 0.9604 \times 5000 = 4802 \approx 4900 .

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A common base amplifier has an input resistance Ri​=20Ω and an output resistance Ro​=100kΩ. If the current gain α=0.98, what is the power gain Ap​ of the amplifier?

Solution

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More Semiconductor Devices practice questions

$A common base amplifier has an input resistance R_{i} = 20 Ω and an output resistance R_{o} = 100 k Ω . If the current gain α = 0.98, what is the power gain A_{p} of the amplifier?$