GATE EC question library

A small percentage of impurity is added to an intrinsic semiconductor at $300 \: K$. Which one of the following statements is true for the energy band diagram shown in the following figure?

Consider the following statements for a metal oxide semiconductor field effect transistor (MOSFET): Which of the above statements are INCORRECT? P and Q P and S Q and R R and S

Consider the constant current source shown in the figure below. Let $\beta$ represent the current gain of the transistor. The load current $I_0$ through $R_L$ is

The following signal $V_i$ of peak voltage $8 \: V$ is applied to the non-inverting terminal of an ideal Op-amp.The transistor has $V_{EE}=0.7 \: V$, $\beta=100; \: V_{LED}=1.5 \: V$, $V_{CC}=10 \: V$ and $– V_{CC}= – 10 \:V$. The number of times the LED glows is ________

Consider the oscillator circuit shown in the figure. The function of the network (shown in dotted lines) consisting of the $100 \: k \Omega$ resistor in series with the two diodes connected back-to-back is to:

The block diagram of a frequency synthesizer consisting of a Phase Locked Loop (PLL) and a divide-by-$N$ counter (comprising $\div 2, \div 4, \div 8, \div 16$ outputs) is sketched below. The synthesizer is excited with a $5$ kHz signal (Input $1$). The free-running frequency of the PLL is set to $20$ kHz. Assume that the commutator switch makes …

The output of the combinational circuit given below is

What is the voltage $V_{out}$ in the following circuit ?

Match the inferences $X$, $Y$ and $Z$, about a system,to the corresponding properties of the elements of first column in Rouths' Table of the system characteristic equation. …

A closed-loop control system is stable if the Nyquist plot of the corresponding open-loop transfer function

Consider binary data transmission at a rate of $56$ kbps using baseband binary pulse amplitude modulation (PAM) that is designed to have a raised-cosine spectrum. The transmission bandwidth (in kHz) required for a roll-off factor of $0.25$ is ________

A superheterodyne receiver operates in the frequency range of $58$ MHz – $68$ MHz. The intermediate frequency $f_{IF}$ and local oscillator frequency $f_{LO}$ are chosen such that $f_{IF} \leq f_{LO}$. It is required that the image frequencies fall outside the $58$ MHz – $68$ MHz band. The minimum required $f_{IF}$ (in MHz) is _________

The amplitude of a sinusoidal carrier is modulated by a single sinusoid to obtain the amplitude modulated signal $s(t) = 5 \cos1600 \pi t + 20 \cos 1800 \pi t + 5 \cos 2000 \pi t$. The value of the modulation index is _________

Concentric spherical shells of radii $2$m, $4$m, and $8$ m carry uniform surface charge densities of $20 \: nC/m^2$, $– 4 \: nC/m^2$ and $\rho_s$ respectively. The value of $\rho_s$ ($nC/m^2$) required to ensure that the electric flux density $\overrightarrow D$ = $\overrightarrow 0$ at radius $10$ m is ________

The propagation constant of a lossy transmission line is $(2+j5) m^{-1}$ and its characteristic impedance is $(50+j0) \Omega$ at $\omega = 10^6 rad \: s^{-1}$. The values of the line constants L,C,R,G are,respectively,

The integral $\frac{1}{2\pi} \iint_D(x+y+10) \,dx\,dy$, where $D$ denotes the disc: $x^2+y^2\leq 4$,evaluates to _________

A sequence $x[n]$ is specified as $\begin{bmatrix}x[n] \\x[n – 1]\end{bmatrix}=\begin{bmatrix}1&1\\1&0\end{bmatrix}^n\begin{bmatrix}1\\0\end{bmatrix}$,for $n \geq 2$. The initial conditions are $x[0] = 1$, $x[1] = 1$, and $x[n] = 0$ for $n < 0$. The value of $x[12]$ is _________

In the following integral, the contour $C$ encloses the points $2 \pi j$ and $- 2\pi j$ $$-\frac{1}{2\pi}\oint_C\frac{\sin z}{(z-2\pi j)^3} \,dz$$ The value of the integral is _________

The region specified by $\{ (\rho,\varphi,z):3 \leq\rho\leq 5,\frac{\pi}{8}\leq\varphi\leq\frac{\pi}{4}, \: 3\leq z\leq4.5\}$ in cylindrical coordinates has volume of _________

The Laplace transform of the casual periodic square wave of period $T$ shown in the figure below is