In regard to improving the performance of a BJT differential

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In regard to improving the performance of a BJT differential amplifier, consider the following four statements:
(1) The value of ADM is increased by increasing R_E
(2) The value of CMRR is increased by increasing R_E
(3) Increasing R_E increases A_CM
(4) Increasing β₀ and R₀ increases A_DM
Of these, the true statements are:

1. only 1, 2
2. only 2, 3
3. only 3, 4
4. only 2, 4

Correct Option: D

In the BJT differential amplifier

A_DM =	1	·	β₀ · R_c	and
	2		(R_S + h_ie)

C_MRR =	A_DM	‚ and
	A_CM

A_CM =	–B₀ · R_c
	R_S + h_ie + (1 + β_o)2R_E

Thus, in order to high C_MRR.
β & R_c should be high and ∝ A_DM
RE should be high and ∝ C_MRR
Hence alternative (D) is correct choice.