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The gm of the MOS transistor is 4 mA/V and the common base current gain of the bipolar transistor is 0.99. The transconductance of the composite transistor as shown in the figure below will be—
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- 39.6 mA/V
- 3.96 mA/V
- 1.98 mA/V
- 0.99 mA/V
Correct Option: B
Emitter current (IE) = gm Vin (in the case of BJT)
| α (bipolar) = | IE |
IC = α IE
IC = α. gm Vin …(i)
| gm (overall) = | …(ii) | Vin |
from (i) and (ii)
| gm (overall) = | Vin |
= α. gm = .99 × 4 m A/V
= 3.96 m A/V
Hence alternative (B) is the correct answer.
