ISRO Scientist or Engineer Electronics 2020

A radarreceiver has a detection SNR threshold of 10 dB for a 4 MHz bandwidthsignal at 300 MHzfrequency.If the transmit EIRP of the radar is 40 dBW andreceive $$\frac{G}{T}$$ is 10 $$\frac{dB}{K}$$, what is the minimum RadarCross Section (in dB-meter square) detectable at 10 km range? (Given : 10 log $$(4\pi)$$ = 11, 10 log(k) = -228.6, k is Boltzmannconstant).

A source generates four messages m1, m2, m3 and m4,with probabilities 0.5, 0.25, 0.125 respectively.The messages are generated independently of each other.A source coder assigns binary code to each message. Which of the following code has minimum average length and is also uniquely decodable (sequnece as per m1, m2, m3, m4)?

For the given circuit, switch remains closed for a long time and opens at t = 0 seconds. Assuming ideal model for every device find steady state magnitude of voltage at capacitor.

For the given circuit, Aspect ratio of $$M_{1}$$, transistor is $$\frac{20}{0.5}, I_{D_{1}} = 200 \mu A, V_{THO} = 0.6 V, 2 \phi_f = 0.81 V, \gamma = 0.4 V^{2}$$ and $$\mu_{n} C_{ox} = 59.5 \mu A/V^2$$. If $$V_{in} = 1.2 V$$, find the minimum value of aspect ratio of $$M_{2}$$ transistor to ramin saturated $$(\sqrt{10} = 3.16)$$

Two coherent microwave power sources of same frequency f, each generating P Watts of average power ,are combined using a four port network in the following manner

If the S-parameter of the 4-port network are $$\begin{bmatrix}0 & \frac{j}{\sqrt{2}}& \frac{-1}{\sqrt{2}}&0 \\\frac{j}{\sqrt{2}} & 0 & 0 &\frac{-1}{\sqrt{2}}\\\frac{-1}{\sqrt{2}} & 0& 0& \frac{j}{\sqrt{2}}\\0& \frac{-1}{\sqrt{2}}& \frac{j}{\sqrt{2}}&0\end{bmatrix}$$ what should be the phase difference between the inputs to maximize the output at port 2 and what is maximum the power?

Which of the following statement is wrong?

Which of the following statementis correct?

Which one plot gives the closest resemblanceto the stability factor $$S(I_{co})$$ of emitter bias configiuration of BJT with respect to $$\frac{R_{E}}{R_{B}}$$? ($$R_{E}$$ is the emitter resistance and $$R_{B}$$ is the base resistance)

For the given Amplifier Circuit find the input cutoff frequency. FET parameters are $$g_{m} = 4 mA/V, C_{gs} = 4 pf, r_{ds} = 40 K Ω, C_{gd} = 2pF$$

Which of the following digital devices requires an external refresh circuit?