Physics : Semiconductor Electronics: Materials, Devices and Simple Circuits

In a common emitter (CE) amplifier having a voltage gainG, the transistor used has transconductance 0.03 mho and current gain 25. If the above transistor is replaced with another one with transconductance 0.02 mho and current gain 20, the voltage gain will

• 2/3 G

• 1.5 G

• 1/3 G

• 1/3 G

In an n-type semiconductor, which of the following statement is true?

• Electrons are majority carriers and trivalent atoms are dopants

• Electrons are minority carriers and pentavalent atoms are dopants

• Holes are minority carriers and pentavalent atoms are dopants

• Holes are minority carriers and pentavalent atoms are dopants

Symbolic representation of four logic gates are shown as,




Pick out which ones are for AND, NAND and NOT gates, respectively.

• (iii), (ii)  and (i)

• (iii), (ii) and (i)

• (ii), (iv), and (iii)

• (ii), (iv), and (iii)

If a small amount of antimony is added to germanium crystal

• the antimony becomes an acceptor atom

• there will be more free electrons than holes in the semiconductor

• its resistance is increased

• its resistance is increased

In forward biasing of the p - n junction

• the positive terminal of the battery is connected to n - side and the depletion region becomes thin

• the positive terminal of the battery is connected to n- side and the depletion region becomes thick

• the positive terminal of the battery is connected to p - side and the depletion region become thin

• the positive terminal of the battery is connected to p - side and the depletion region become thin

A transistor is operated in common emitter configuration V_C = 2V such that change n the base current from 100 µA to 300 µA produces a change in the collector current from 10 mA to 20 mA. The current gain is

• 75

• 100

• 25

• 25

The input signal given to a CE amplifier having a voltage gain of 150 is  The corresponding output signal will be

In the following figure, the diodes which are forward biased, are

Pure Si at 500 K has an equal number of the electron (n_e) and hole (n_h) concentrations of 1.5 x 10¹⁶ m^-3.Doping by indium increases n_h to 4.5 x 1022 m ^-3.The doped semiconductor is of 

• n- type with electron concentration n_e = 5 x 10²² m ^-3

• P- type with electron concentration n_e = 2.5 x 10¹⁰ m ^-3

• n- type with electron concentration n_e = 2.5 x 10²³ m ^-3

• n- type with electron concentration n_e = 2.5 x 10²³ m ^-3

A Zener diode, having breakdown voltage equal to 15 V, is used in a voltage regulator circuit shown in the figure. The current through the diode is

• 10 mA

• 15 mA

• 20 mA

• 20 mA