GATE 2023 - Important Concepts, Short cuts, Complete Solutions, Examples and Practice Problems: GATE 1995

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GATE 1995 ECE Analog Circuits (Analog Electronics) - Video Solutions

1. A change in the value of the emitter resistance, R_E, in a differential amplifier
a. affects the difference mode gain A_d
b. affects the common mode gain A_c
c. affects both A_d and A_c
d. does not affect both A_d and A_c.

Solution : https://www.youtube.com/watch?v=czxo7TomyPc

2. To obtain very high input and output impedance in a feedback amplifier, the topology mostly used is
a. Voltage Series
b. Current Series
c. Voltage Shunt
d. Current Shunt

Solution : https://www.youtube.com/watch?v=xfuv73dQbBA

3. In the given circuit, if the voltage V₊ and V_{_} are to amplified by the same factor, the value of R should be _________

Solution : https://www.youtube.com/watch?v=iyaRnnLhxNI

4. An NPN transistor under forward active mode of operation is biased at I_c = 1 mA, and has a total emitter base capacitance C_K of 12 pF, and the base transit time τ_F of 260 psec. Under this condition, the depletion capacitance of the emitter base junction is _____________

Solution : https://www.youtube.com/watch?v=faoewgwLY0o

5. An RC coupled amplifier is assumed to have a single pole low frequency transfer function. The maximum lower cutoff frequency allowed for the amplifier to pass 50 Hz square wave with no more than 10% tilt is ______________

Solution : https://www.youtube.com/watch?v=Y7Pez6ot4bQ

6. An OP-AMP is used as a zero crossing detector. If the maximum output available from the OP-AMP is ±12 volts peak to peak, and the slew rate of the OP-AMP is 12 V/µsec, then the maximum frequency of the input signal that can be applied without causing a reduction in the peak to peak output is _____________

Solution : https://www.youtube.com/watch?v=xMs3KYXPxeQ

7. A power amplifier delivers 50W output at 50% efficiency. The ambient temperature is 25^oC. If the maximum allowable junction temperature is 150^oC, then the maximum thermal resistance ø_jc that can be tolerated is __________

Solution : https://www.youtube.com/watch?v=aOpeF9Z9hlQ

8. An amplifier has an open loop gain of 100, and its lower and upper cutoff frequency of 100 Hz and 100 kHz respectively. A feedback network with a feedback factor of 0.99 is connected to the amplifier. The new lower and upper cutoff frequencies are at __________ and ________

Solution : https://www.youtube.com/watch?v=R7lcv_H47gE

9. Match the following:
a) CC amplifier 1) provides voltage gain but no current gain
b) CE amplifier 2) provides current gain but no voltage gain
c) CB amplifier 3) provides neither voltage nor power gain
4) provides neither current nor power gain
5) provides both voltage and current gain

Solution : https://www.youtube.com/watch?v=6I1uAhJPB10

10. Sketch the output as a function of the input voltage (for negative values) for circuit shown below. Assume ideal operational amplifier and diode forward voltage drop as zero.

Solution: https://www.youtube.com/watch?v=ulb3JFwnZDs

11. The waveform input to the sweep generator circuit shown in figure, is a square wave of period 2 msec and amplitude varying between 0 and 12 volts.

a. Draw the waveform V_o(t), in relation to the input
b. Specify V_o(t) determine the voltage levels and the time constants involved.

Solution: https://www.youtube.com/watch?v=MqLJPriVFVw

12. In the JFET circuit shown, assume that R₁//R₂ = 1 MΩ and the total stray capacitance at the output to be 20 pF.

Determine the upper cutoff frequency of the amplifier.

Solution: https://www.youtube.com/watch?v=joc09FhNQI8

13. Show that the circuit shown in figure is double integrator. In other words, prove that the transfer gain is given by V_o(s)/V_s(s) = 1/(SCR)², assume ideal operational amplifier.

Solution: https://www.youtube.com/watch?v=kIlrli8NFJ0

14. In the amplifier circuit shown, determine the value of R such that Q₂ is biased at V_CE2 = 7.5 volts. Assume Q₁ and Q₂ to be identical with V_BE = 0.7 volts.

Also determine the small signal input impedance of Q₁ and Q₂, if both of them have β = 200. Use V_T = 26 mV.

Solution: https://www.youtube.com/watch?v=CiBKrmFWjC8

GATE 1995 ECE Video Solutions on Digital Circuits (Digital Electronics)

1. The output of the circuit shown in figure is equal to

Solution: https://www.youtube.com/watch?v=f86allXIvS0

2. The minimum number of NAND gates required to implement the Boolean function A + AB’ + AB’C is equal to
a. Zero
b. 1
c. 4
d. 7

Solution: https://www.youtube.com/watch?v=ZxI6mFEl4Hc

3. A switch-tail ring counter is made by using a single D flip flop. The resulting circuit is a
a. SR flip flop
b. JK flip flop
c. D flip flop
d. T flip flop

Solution: https://www.youtube.com/watch?v=NgHdSqy1YKw

4. When a CPU is interrupted, it
a. Stops executing of instructions
b. Acknowledges interrupt and branches of subroutine
c. Acknowledges interrupt and continues
d. Acknowledges interrupt and waits for the next instruction from the interrupt device
Answer:
Solution:

5. The minimum number of MOS transistors required to make a dynamic RAM cell is
a. 1
b. 2
c. 3
d. 4

Solution: https://www.youtube.com/watch?v=0zh1pqRqIPY

6. An SR latch is a
a. Combinational circuit
b. Synchronous sequential circuit
c. One bit memory element
d. One clock delay element

Solution: https://www.youtube.com/watch?v=C8x2OcVIKh8

7. A ‘DMA’ transfer implies
a. Direct transfer of data between memory and accumulator
b. Direct transfer of data between memory and I/O devices without use of µP
c. Transfer of data exclusively within µP registers
d. A fast transfer of data between µP and I/O devices

Solution:

8. An ‘Assembler’ of a microprocessor is used for
a. Assembly of processors in a production line
b. Creation of new program’s using different modules
c. Translation of a program form assembly language to machine language
d. Translation of a higher level language into English text

Solution:

9. For a TTL gate, match the following

Solution: https://www.youtube.com/watch?v=TSWQwxxgVO4

10. For an ADC, match the following

Solution: https://www.youtube.com/watch?v=QS5jEa8E8r4

11. A ROM is used to implement the Boolean functions given below.

a. What is the minimum size of the ROM required?
b. Determine the data in each location of the ROM

Solution: https://www.youtube.com/watch?v=kqnpFRi_gYQ

12. A hypothetical CPU has a parallel address bus, a parallel data bus, a RD and WR active LOW signals. Two ROMs of size 4K words each and two RAMs of sizes 16K and 8K words, respectively, are to be connected to the CPU. The memories are to be so connected that they fill the address space of the CU as per the memory map shown in the figure. Assuming tat chip select signals are active LOW.

a. What is the number of lines in the address bus of the CPU?
b. Determine the values of address X, Y, Z and W as decimal numbers.
c. Using a 2 to 4 decoder and some additional gates, draw a circuit for the decoding logic.

Solution: https://www.youtube.com/watch?v=7xJmGpkvMAo

13. A ‘code converter’ is to be designed to convert from the BCD (5421) code to normal BCD (8421) code. The input BCD combinations for each digit are given below. A block diagram of the converter is shown in figure.
a. Draw K- map for outputs W, X, Y and Z
b. Obtain minimized expression for the outputs W, X, Y and Z

Solution: https://www.youtube.com/watch?v=S-O75HI10qY

GATE 1995 Video Solution on EDC (Electronic Devices and Circuits)

1. The drift velocity of electrons, in silicon
a. Is proportional to the electric field for all values of electric field
b. Is independent of the electric field
c. Increases at low values of electric field and decreases at high values of electric field exhibiting negative differential resistance.
d. Increases linearly with electric field at low values of electric field and gradually saturates at higher values of electric field.

Solution : https://www.youtube.com/watch?v=RJPyzF2-gcc

2. The diffusion potential across a PN junction
a. Decreases with increasing doping concentration
b. Increases with decreasing band gap
c. Does not depend on doping concentration
d. Increases with increase in doping concentrations

Solution : https://www.youtube.com/watch?v=aoeFCtKOuq8

3. The breakdown voltage of a transistor with its base open is BV_CEO, that with emitter open is B_VCBO then
a. BV_CEO = BV_CBO
b. BV_CEO > BV_CBO
c. BV_CEO < BV_CBO
d. BV_CEO not related to BV_CBO

Solution : https://www.youtube.com/watch?v=sX-wk56YviU

4. In a p-type silicon sample, the hole concentration is 2.25 X 10¹⁵ cm^-3. If the intrinsic carrier concentration is 1.5 X 10¹⁰ cm^-3, the electron concentration is
a. Zero
b. 10¹⁰ cm^-3
c. 10⁵ cm^-3
d. 1.5 X 10¹⁰ cm^-3

Solution : https://www.youtube.com/watch?v=j2CvMPiwMW8

5. A Zener diode works on the principle of
a. Tunneling of charge carriers across the junction
b. Thermionic emission
c. Diffusion of charge carriers across the junction
d. Hopping of charge carriers across the junction

Solution : https://www.youtube.com/watch?v=4wq0h-QhMjk

6. A BJT is said to be operating in the saturation region, if
a. Both the junctions are reverse biased
b. Base emitter junction is in reverse biased, and base collector junction is forward biased
c. Base emitter junction is in forward biased, and base collector junction is reverse biased
d. Both the junctions are forward biased

Solution : https://www.youtube.com/watch?v=vafpJ7FB9xE

7. The depletion capacitance, C_J, of an abrupt PN junction with constant doping on either side varies with reverse bias, V_R as

Solution : https://www.youtube.com/watch?v=H7843qbzIOI

8. The Ebers – Moll model is applicable to
a. Bipolar junction transistors
b. nMOS transistors
c. Unipolar Junction transistors
d. Junction field effect transistors

Solution : https://www.youtube.com/watch?v=Xi6e2_7L2Sk

9. The probability that an electron in a metal occupies the Fermi level at any temperature T is (T > 0^oK)
a. 0
b. 1
c. 0.5
d. none

Solution : https://www.youtube.com/watch?v=FgCetVfygC0

10. A transistor having α = 0.99 and VBE = 0.7 volts, in the circuit shown, then the value of the collector current will be…………

Solution : https://www.youtube.com/watch?v=2SJ3DMImgPk

11. The circuit shown in figure, supplies power to an 8 Ω loud speaker. The values of I_C and V_CE for this circuit will be

Solution : https://www.youtube.com/watch?v=ENXTOwOfeoE

12. An n-channel JFET has I_DSS = 1 mA and V_P = -5 volts. Its maximum Transconductance is ……..

Solution : https://www.youtube.com/watch?v=mXxiWhP59fQ

13. In a Bipolar junction transistor, if

Solution : https://www.youtube.com/watch?v=9FDC-pX_y4s

14. In a JFET, if

Solution : https://www.youtube.com/watch?v=Ll4flWTSUbY

15. In an extrinsic semiconductor, if

4. The area of cross section of the semiconductor is increased
5. The doping concentration is increased

Solution : https://www.youtube.com/watch?v=Zk5QaYZDYbs

16. Two identical silicon junction diodes, D1 and D2 are connected back to back as shown. The reverse saturation current I_S of each diode is 10^-8 Amps and the breakdown voltage is 50 volts. Evaluate the voltage V_D1 and V_D2 across the diode D1 and D2 by assuming KT/q to be 25mV.

Solution : https://www.youtube.com/watch?v=i-pu6FQW5w0

17. Calculate the capacitance of a circular MOS capacitor, of 0.5 mm dia and having a SiO₂ layer of 80 mm thickness, under strong accumulation. Assume the relative dielectric constant of SiO₂, Ԑ_r = 4 and Ԑ_o = 8.854 X 10^-14 F/cm. calculate the breakdown voltage of the capacitor if the dielectric strength of SiO₂ film is 10⁷ V/cm.

Solution : https://www.youtube.com/watch?v=tAtC_pW9Bcw

18. The Fermi level of an n-type germanium film is 0.2 eV above the intrinsic Fermi level towards the conduction band. The thickness of the film is 0.5 µm. Calculate the sheet resistance of the film.
Assume :
n_i = 10¹³ cm^-3,
µ_n = 3500 cm²/V-sec,
µ_p = 1500 cm²/V-sec,
KT/q = 26 mV.

Solution : https://www.youtube.com/watch?v=7q9ggl2_4rk

GATE 1995 ECE Analog Circuits (Analog Electronics) - Video Solutions

GATE 1995 ECE Video Solutions on Digital Circuits (Digital Electronics)

GATE 1995 Video Solution on EDC (Electronic Devices and Circuits)

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