GATE EC question library

The Ebers-Moll model of a $BJT$ is valid

A long-channel $NMOS$ transistor is biased in the linear region with $V_{DS}=50$ $m$ $V$ and is used as a resistance. Which one of the following statement is $NOT$ correct?

Assume that the diode in the figure has $V_{on}=0.7 \:V$, but it otherwise ideal. The magnitude of the current $i_{2}$ in mA) is equal to _________

Resistor $R_{1}$ in the circuit below has been adjusted so that $I_{1}=1$ $mA$. The bipolar transistors $Q1$ and $Q2$ are perfectly matched and have very high current gain, so their base currents are negligible. The supply voltage $V_{cc}$ is $6$ $V$. The thermal voltage $KT/q$ is $26$ $mV$. The value of $R_{2}$ (in $\Omega)$ for …

Which one of the following statements is correct about an ac-coupled common-emitter amplifier operating in the mid-band region?

Transistor geometries in a $CMOS$ inverter have been adjusted to meet the requirement for worst case charge and discharge times for driving a load capacitor $C$. This design is to be converted to that of a $NOR$ circuit in the same technology, so that its worst case charge and discharge times while driving the same capacitor are similar. The channel …

Assume that all the digital gates in the circuit shown in the figure are ideal, the resistor $R=10\Omega$ and the supply voltage is $5\:V$. The $D$ flip-flops $D_{1} \:, D_{2} \:, D_{3} \:, D_{4}$ and $D_{5}$ are initialized with logic values $0,1,0,1$ and $0$, respectively. The clocks has a $30\%$ duty cycle. The average power dissipated (in …

A $4:1$ multiplexer is to be used for generating the output carry of a full adder. $A$ and $B$ are the bits to be added while $C_{in}$ is the input carry and $C_{out}$ is the output carry. $A$ and $B$ are to be used as the select bits with $A$ being the more significant select bit. Which one of the following statements correctly describes the …

The response of the system $G(s)=\frac{s-2}{(s+1)(s+3)}$ to the unit step input $u(t)$ is $y(t)$. The value of $\frac{dy}{dt}$ at $t=0^{+}$ is _________

The number and direction of encirclements around the point $-1+j0$ in the complex plane by the Nyquist plot of $G(s)=\frac{1-s}{4+2s}$ is

A discrete memoryless source has an alphabet $\left \{ a_{1},a_{2}, a_{3},a_{4}\right \}$ with corresponding probabilities $\left \{ \frac{1}{2}, \frac{1}{4},\frac{1}{8},\frac{1}{8}\right \}.$ The minimum required average codeword length in bits to represent this source for error-free reconstruction is _________

A speech signal is sampled at $8$ $kHz$ and encoded into $PCM$ format using $8$ bits/sample. The $PCM$ data is transmitted through a baseband channel via $4$-level $PAM$. The minimum bandwidth (in $kHz$) required for transmission is _________

A uniform and constant magnetic field $\textbf{B}=\hat{z}B$ exists in the $\hat{z}$ direction in vacuum. A particle of mass $m$ with a small charge $q$ is introduced into this region with an initial velocity $\textbf{v}=\hat{x}v_{x}+\hat{z}v_{z}$. Given that $B$, $m$, $q$, $v_{x}$ and $v_{z}$ are all non-zero, which one of the following …

Let the electric field vector of a plane electromagnetic wave propagating in a homogeneous medium be expressed as $\textbf{E}=\hat{x}E_{x}e^{-j(\omega t-\beta z)},$ where the propogation constant $\beta$ is a function of the angular frequency $\omega$. Assume that $\beta (\omega )$ and $E_{x}$ are known and are real. From the information available, …

Light from free space is incident at an angle $\theta _{i}$ to the normal of the facet of a step-index large core optical fibre. The core and cladding refractive indices are $n _{1}=1.5$ and $n _{2}=1.4$, respectively. The maximum value of $\theta _{i}$ (in degrees) for which the incident light will be guided in the core of the fibre is _________

The ordinary differential equation $$\frac{dx}{dt}=-3x+2, \text{ with }x(0) = 1$$ is to be solved using the forward Euler method. The largest time step that can be used to solve the equation without making the numerical solution unstable is _________

Suppose $C$ is the closed curve defined as the circle $x^{2}+y^{2}=1$ with $C$ oreinted anti-clockwise. The value of $\oint$ ( $xy^{2}$ $dx$ + $x^{2}y$ $dy$ )over the curve $C$ equals _________

Two random variables $X$ and $Y$ are distributed according to $$f_{X,Y}(x,y)=\begin{cases} (x+y),& 0\leq x\leq 1,&0\leq y\leq 1\\ 0, & \text{otherwise.} \end{cases}$$ The probability $P(X+Y\leq 1)$ is ________

The matrix $A=\begin{bmatrix} a & 0 &3 &7 \\ 2& 5&1 &3 \\ 0& 0& 2 &4 \\ 0&0 & 0 &b \end{bmatrix}$ has $\text{det}(A) = 100$ and $\text{trace}(A) = 14$. The value of $\mid a-b \mid$ is ________

In the given circuit, each resistor has a value equal to $1\Omega$. What is the equivalent resistance across the terminals $a$ and $b$?