ISRO Scientist or Engineer Electronics 2012


For the following questions answer them individually

Question 1

$$1 cm^{3}$$ of pure Germanium at $$20^\circ$$C contains about $$4.2 \times 10^{22}$$ atoms, $$2.5 \times 10^{13}$$ free electrons and $$2.5 \times 10^{13}$$ holes. 0.001% of Arsenic doping donatesan extra $$10^{17}$$ free electrons in the same volume. The approximate humberof holes in one $$cm^{3}$$ in the doped semiconductor under equilibrium condition is :

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Question 2

Measurementof Hall coefficient enables the determination of :

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Question 3

Siliconis not suitable for fabrication oflight emitting diodes becauseit is :

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Question 4

The band gap of elements arranged in ascendingorderis :

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Question 5

The following statements are made for NMOS & PMOS
1: The carrier mobility in NMOSis higher
2: PMOSrequire less area than NMOS
3: NMOS circuits are smaller than PMOS
4: PMOS are fasterin switching.
Of these, the true statements are -

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Question 6

The following statements are made for FETs
1. In n-channel depletion mode MOSin the active region, the control voltage Veg is negative.
2. NMOSin depletion modeis cut off for $$V_{GS}$$=0
3. NMOSin enhance modeis cut off for $$V_{GS}$$=0
4. There is no path betweensource and drain in the enhancement mode
Of these, the true statementsare :

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Question 7

Special handling precautions should be taken when working with MOS devices. The statement whichis nottrueis :

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Question 8

If the input to the circuit of Figure is a sine wave, then the output will be :

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Question 9

A high gain OpAmp has $$R_{f} = 10^{5} Ω  \&  R_{f} = 10^{3} Ω$$. The correct statement is:

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Question 10

For various typesofoscillators, the correct statementis:

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