GATE EC question library

For a superheterodyne receiver, the intermediate frequency is $15\ MHz$ and the local oscillator frequency is $3.5\ GHz$. If the frequency of the received signal is greater than the local oscillator frequency, then the image frequency (in $MHz$) is _______

An analog baseband signal, bandlimited to $100\ Hz$, is sampled at the Nyquist rate. The samples are quantized into four message symbols that occur independently with probabilities $p_1 = p_4 = 0.125$ and $p_2 = p_3$. The information rate (bits/sec) of the message source is _______

A binary baseband digital communication system employs the signal $$p(t) = \begin{cases}\large\frac{1}{\sqrt T_s},&0\leq t\leq T_s \\ \: 0, & \text{otherwise} \end{cases}$$ for transmission of bits. The graphical representation of the matched filter output $y(t)$ for this signal will be

If a right-handed circularly polarized wave is incident normally on a plane perfect conductor, then the reflected wave will be

Faraday’s law of electromagnetic induction is mathematically described by which one of the following equations?

The particular solution of the initial value problem given below is $$\frac{d^2y}{dx^2}+12\frac{dy}{dx}+36y=0\hspace{0.3cm} \text{ with } \hspace{0.3cm}y(0)=3\hspace{0.3cm} \text{ and }\hspace{0.3cm} \frac{dy}{dx} \bigg| _{x=0} =-36$$

If the vectors $e_1=(1,0,2)$, $e_2=(0,1,0)$ and $e_3=(-2,0,1)$ form an orthogonal basis of the three-dimensional real space $\mathbb{R}^3$, then the vector $\textbf{u}=(4,3,-3)\in \mathbb{R}^3$ can be expressed as

A triangle in the $xy$-plane is bounded by the straight lines $2x=3y, \: y=0$ and $x=3$. The volume above the triangle and under the plane $x+y+z=6$ is _______

The values of the integral $\large\frac{1}{2\pi j}\oint_c\frac{e^z}{(z-2)} \small dz$ along a closed contour $c$ in anti-clockwise direction for the point $z_0=2$ inside the contour $c$, and the point $z_0=2$ outside the contour $c$, respectively,are

A signal $2 \cos(\frac{2\pi}{3}t)-\cos(\pi t)$ is the input to an LTI system with the transfer function $$H(s)=e^s+e^{-s}.$$ If $C_k$ denotes the $k^{th}$ coefficient in the exponential Fourier series of the output signal, then $C_3$ is equal to

The ROC (region of convergence) of the $z$-transform of a discrete-time signal is represented by the shaded region in the $z$-plane. If the signal $x[n]=(2.0)^{\mid n\mid},-\infty<n<+\infty$, then the ROC of its $z$-transform is represented by

Assume that the circuit in the figure has reached the steady state before time $t = 0$ when the $3\;\Omega$ resistor suddenly burns out, resulting in an open circuit. The current $i(t)$ (in ampere) at $t=0^+$ is _______

In the figure shown, the current $i$ (in ampere) is _________

The $z$-parameter matrix $\begin{bmatrix} z_{11} &z_{12}\\ z_{21} &z_{22} \end{bmatrix}$ for the two-port network shown is

A continuous-time speech signal $x_a(t)$ is sampled at a rate of $8\:kHz$ and the samples are subsequently grouped in blocks, each of size $N$. The DFT of each block is to be computed in real time using the radix-$2$ decimation-in-frequency FFT algorithm. If the processor performs all operations sequentially, and takes $20\:\mu s$ for computing …

The direct form structure of an FIR (finite impulse response) filter is shown in the figure. The filter can be used to approximate a

The injected excess electron concentration profile in the base region of an $npn$ BJT, biased in the active region, is linear, as shown in the figure. If the area of the emitter-base junction is $0.001\:cm^2 ,\mu_n=800cm^2/(V-s)$ in the base region and depletion layer widths are negligible, then the collector current $I_c$(in mA) at room temperature is …

Figures I and II show two MOS capacitors of unit area. The capacitor in Figure I has insulator materials $X$ (of thickness $t_1 = 1$ nm and dielectric constant $\varepsilon_1=4$) and $Y$ (of thickness $t_2 = 3$ nm and dielectric constant $\varepsilon_2 = 20$). The capacitor in Figure II has only insulator material $X$ of thickness $t_{Eq}$. …

The $I-V$ characteristics of the zener diodes $D1\:\text{and}\:D2$ are shown in Figure I. These diodes are used in the circuit given in Figure II. If the supply voltage is varied from $0$ to $100$ V,then breakdown occurs in

For the circuit shown in the figure, $R_1=R_2=R_3=1\;\Omega,\;L=1\:\mu H$ and $C=1\:\mu F$. If the input $V_{in}=\cos(10^6t)$, then the overall voltage gain $(V_{out}/V_{in})$ of the circuit is _________