Question

Consider the circuit shown in the figure below.

$\text{The diodes}{D}_1\text{and}{D}_2\text{are non-ideal with cut-in voltages of 0.7 V and forward resistance}{r}_f=0\Omega \text{and}{r}_{rev}=\infty \text{. The Zener diode}{D}_z\text{has forward voltage drop of 0.7 V and a Zener voltage of 5 V. If an input sine wave of maximum peak amplitude of 10 V is applied at}{V}_{in}\text{, then the transfer characteristic of the circuit can be represented as}$

• A.
• B.
• C.
• D.

Answer 1

The correct option is A

Ans : (c)

$\text{For}{V}_{in}>1.4V,D_z\text{and}{D}_1\text{will be forward biased and thus,}{V}_0=V_{in}-1.4V$
$\text{and for}{V}_{in}<-5.7V.$
$\text{diodes}{D}_2\text{will be in forward biased region and the Zener diode will be in breakdown region.}$
$V_0=V_{in}+5.7V$
$\text{for}-5.7V\le V_{in}\le 1.4V\text{, the diodes will be off hence,}$
$V_0=0V$
thus, the characteristic curve can be drawn as,