Solved Question Paper of Recruitment Test (Computer Based Recruitment Test) conducted by UPSC for the Post of Lecturer (Electronics & Communications Engineering) in Directorate of Training and Technical Education (DTTE), Government of National Capital Territory of Delhi (GNCTD) held on 10.03.2019.

1. Which of the following is obtained by drawing a single crystal from a melt of germanium whose type is changed during the drawing process by adding first 𝑝-type and then 𝑛- type impurities?

1. Alloy junction

2. Diffused junction

3. Grow junction

(a) 1 only

(b) 2 only

(c) 3 only

(d) 1, 2 and 3

Answer: (c)

2. Circuits that are used to eliminate portions of a signal that are above or below a specified level are called:

(a) Clampers

(b) Clippers

(c) Voltage doublers

(d) Detectors

Answer: (b)

3. The circuit consisting of an op-amp connected in a non-inverting configuration and two RC networks connected as the frequency-selecting feedback circuit is called:

(a) Phase shift oscillator

(b) Colpitts oscillator

(c) Hartley oscillator

(d) Wien-bridge oscillator

Answer: (d)

4. 

(a) 0.4 Ω

(b) 0.2 Ω

(c) 0.1 Ω

(d) 0.05 Ω

Answer: (c)

5. 

(a) 1.46 𝑘Ω and 30 𝑘Ω

(b) 1.46 𝑘Ω and 50 𝑘Ω

(c) 1.64 𝑘Ω and 50 𝑘Ω

(d) 1.64 𝑘Ω and 30 𝑘Ω

Answer: (b)

6. Since the ideal op-amp responds only to the difference between the two input voltage signals v1 and v2. It maintains a zero output signal for v1=v2. When v1=v2≠0, the characteristic is called:

(a) Common mode rejection

(b) Common mode input signal

(c) Negative supply voltage

(d) Positive supply voltage

Answer: (b)

7. The output voltage is the sum of the input voltages, with different weighting factors. This circuit is called:

(a) Non inverting summing amplifier

(b) Ideal op-amp

(c) Inverting summing amplifier

(d) Non inverting amplifier

Answer: (c)

8. 
 then output voltage follows the input; this op-amp circuit is called:

(a) Basic amplifier

(b) Voltage follower

(c) Summing amplifier

(d) Non inverting amplifier

Answer: (b)

9. What is the output voltage of an op-amp for input voltages of V𝑖1=150 𝜇V , V𝑖2=140 𝜇V with amplifier differential gain of A𝑑=4000 and the value of CMRR =100?

(a) 72.2 𝑚V

(b) 63.4 𝑚V

(c) 54.6 𝑚V

(d) 45.8 𝑚V

Answer: (d)

10. 

(a) 26 𝑑B

(b) 22 𝑑B

(c) 18 𝑑B

(d) 12 𝑑B

Answer: (b)