The circuit given below employs a silicon transistor with

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The circuit given below employs a silicon transistor with the β = 50. The value of biasing resistance R_b for maximum symmetrical swing at the output should be—

1. 120 K
2. 78 K
3. 193 K
4. 122 K

Correct Option: C

The given circuit (i.e., fig - 1)
In order to achieve maximum symmetrical swing at the output the transistor must be biased in the saturation region.
i.e. V₀ = V_CE = 0·2V
From below figure, (i.e., fig - 2)

I_C =		V_CC – V_CE	=	20 – 0·2	= 4·95 mA
		4K		4K

and I_B =	V_CC – V_BE
	R_B ^-3

or R_B =		V_CC – V_BE	=	V_CC – V_BE
		I_B		I_C / β

=	= 20 – 0·7	≈ 193K
	4.95 / 50

Hence alternative (C) is the correct choice.