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In a common emitter (CE) amplifier having a voltage gain G, the transistor used has transconductance 0.03 mho and current gain 25. If the above transistor is replaced with another one with transconductance 0.02 mho and current gain 20, the voltage gain will be
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- 1.5 G
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1 G 3 -
5 G 4 -
2 G 3
Correct Option: D
Voltage gain
| Av = β | Rin |
| ⇒ G = 25 | ...............(i) | Rin |
Transconductance
| gm = | Rin |
| Rin = α . | = | |||
| gm | 0.03 |
Putting this value of Rin in eqn. (i)
| G = 25 | × 0.03 .....(ii) | 25 |
| ∴ G' = 20 | × 0.02 .....(ii) | 20 |
From eqs. (ii) and (iii)
Voltage gain of new transistor
| G’ = | G | 3 |
