Thursday, 6 June 2013

Video Solutions for GATE 2005 ECE : Two Mark Questions (Electron Devices)

1.  A silicon sample A is doped with 1018 atoms / cm3 of boron. 

     Another sample B of identical dimensions is doped with 1018 

     atoms /cm3 of phosphorous. The ratio of electron to hole 

     mobility is 3. The ratio of conductivity of the sample A to B is 

2.  A silicon PN junction diode under reverse bias has depletion 

     region of width 10µm. the relative permittivity of silicon Ɛr is

     11.7 and the permittivity of free space Ɛo = 8.85x10-12 F/m. the

     depletion capacitance of the diode per square meter is

3.  For an npn transistor connected as shown in figure, 

    VBE = 0.7 volts. Given that reverse saturation current of the  

    junction at room temperature 300oK is 10-13 Amp, the emitter 

    current is 

4.  For an n-channel MOSFET and its transfer curve shown in 

     figure, the threshold voltage is

5. The zener diode in the regulator circuit shown in figure has a 

    zener voltage of 5.8 volts and a zener knee current of 0.5 mA. 

    The maximum load current drawn from this circuit ensuring

     proper functioning over the input voltage range between 20 

     and 30 volts is 

6. Both transistors T1 and T2 in figure have a threshold voltage of 

    1 volt. The device parameters k1 and k2 of T1 and T2 are , 

    36 µA/V2 and 9 µA/V2 , respectively. The output voltage Vo is 

7. A MOS capacitor made using p type substrate is in the 

    accumulation mode. The dominant charge in the channel

    is due to the presence of 

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