Multiple choice

In an ideal differential amplifier shown in figure, a large value of RE

  1. increases both the differential and common-mode gains

  2. increases the common-mode gain only

  3. decreases the differential mode gain only

  4. decreases the common-mode gain only
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Common mode gain

$$ A_{CM} = -\dfrac{R_C}{2R_E}$$

And differential mode gain

$$A_{DM} = - g_m R_C$$

Thus only common mode gain depends on $R_E$ and for large value of $R_E$ it decreases.

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