Semiconductor Electronics: Materials, Devices and Simple Circuits

The inputs and outputs for different time intervals are given below the NAND gate

The values taken by P, Q, R, S are respectively

• 1, 1, 1, 0

• 0, 1, 0, 1

• 0, 1, 0, 0

• 1, 0, 1, 1

If α and β are the current gain in the CB and CE configurations respectively of the transistor circuit, then $\frac{\mathrm{\beta } - \mathrm{\alpha }}{\mathrm{\alpha \beta }}$

• infinite

• 1

• 2

• 0.5

A silicon specimen is made into a p-type semiconductor by doping, on an average, one indium atom per 5 x 10⁷ silicon atoms. If the number density of atoms in the silicon specimen is 5 x 10²⁸ atom/m³, then the number of acceptor atoms in silicon per cubic centimetre will be

• 2.5 × 10³⁰ atom/cm³

• 2.5 × 10³⁵ atom/cm³

• 1 × 10¹³ atom/cm³

• 1 × 10¹⁵ atom/cm³

In a common-emitter amplifier, the load resistance of the output circuit is 1000 times the resistance of the input circuit. If α = 0.98, then voltage gain is

• 49 × 10³

• 2.5 × 10²

• 1.5 × 10²

• 4.9

If D_e, D_b and D_c are the doping levels of emitter, base and collector respectively of a transistor, then

• D_e = D_b = D_c

• D_e < D_b = D_c

• D_e > D_c > D_b

• D_e < D_b < D_c

The relation between α and β parameters of a transistor is

• $\mathrm{\alpha } = \frac{1 + \mathrm{\beta }}{\mathrm{\beta }}$

• $\mathrm{\alpha } = \frac{1 - \mathrm{\beta }}{\mathrm{\beta }}$

• $\mathrm{\alpha } = \frac{\mathrm{\beta }}{1 + \mathrm{\beta }}$

• $\mathrm{\alpha } = \frac{\mathrm{\beta }}{1 - \mathrm{\beta }}$

A p-n junction in series with a resistance of 5 km is connected across a 50 V DC source. If the forward bias resistance of the junction is 50 Ω, the forward bias current is

• 8.8 mA

• 1 mA

• 9.9 mA

• 20 mA

A transistor connected at common-emitter mode contains load resistance of 5 kΩ and an input resistance of 1 kΩ. If the input peak voltage is 5 mV and the current gain is 5O, find the voltage gain

• 250

• 500

• 125

• 50

The depletion layer of a p-n junction

• is of constant width irrespective of the bias

• acts like an insulating zone under reverse bias

• has a width that increases with an increase in forward bias

• is depleted of ions

For the given circuit shown below, to act as full wave rectifier, the AC input should be connected across ....and .... and the DC output would appear across ...... and.....

• B and D and A and C

• B and A and C and D

• C and A and B and D

• C and D and B and A