GATE EC question library

Let $\text{M}$ be a real $4\times 4$ matrix. Consider the following statements: $S1: M$ has $4$ linearly independent eigenvectors. $S2: M$ has $4$ distinct eigenvalues. $S3: M$ is non-singular (invertible). Which one among the following is TRUE?

Let $f\left ( x,y \right )=\dfrac{ax^{2}+by^{2}}{xy},$ where $a$ and $b$ are constants. If $\dfrac{\partial f}{\partial x}=\dfrac{\partial f}{\partial y}$ at $x = 1$ and $y = 2$, then the relation between $a$ and $b$ is

A discrete-time all-pass system has two of its poles at $0.25\angle 0^{\circ}$ and $2\angle 30^{\circ}$. Which one of the following statements about the system is TRUE?

Let $\text{x(t)}$ be a periodic function with period $\text{T = 10}$.The Fourier series coefficients for this series are denoted by $a_{k},$ that is $$x\left ( t \right )=\sum ^{\infty }_{k=-\infty }a_{k}e^{jk\:\frac{2\pi }{T}t}$$ The same function $x(t)$ can also be considered as a periodic function with period ${T}'=40.$ Let $b_{k}$ be the …

Consider the following amplitude modulated signal: $$s\left ( t \right )=\cos\left ( 2000\:\pi t \right )+4\cos\left ( 2400\:\pi t \right )+ \cos\left ( 2800\:\pi t \right ).$$The ratio (accurate to three decimal places) of the power of the message signal to the power of the carrier signal is _________.

Consider a binary channel code in which each codeword has a fixed length of $5\: bits$. The Hamming distance between any pair of distinct codewords in this code is at least $2$. The maximum number of codewords such a code can contain is __________.

A binary source generates symbols $X\in \left \{ -1,1 \right \}$ which are transmitted over a noisy channel.The probability of transmitting $X=1$ is $0.5.$ Input to the threshold detector is $R=X+N$.The probability density function $f_{N}\left ( n \right )$ of the noise $\text{N}$ is shown below. If the detection threshold is zero, then the …

A $\text{p-n}$ step junction diode with a contact potential of $0.65\:V$ has a depletion width of $1\:\mu m$ at equilibrium. The forward voltage (in volts, correct to two decimal places) at which this width reduces to $0.6\:\mu m$ is __________.

A traffic signal cycles from $\text{ GREEN to YELLOW, YELLOW to RED and RED to GREEN.}$ In each cycle, $\text{GREEN}$ is turned on for $70$ seconds,$\text{YELLOW}$ is turned on for $5$ seconds and the $\text{RED}$ is turned on $75$ seconds. This traffic light has to be implemented using a finite state machine $\text{(FSM)}$. The only input to …

There are two photolithography systems: one with light source of wavelength $\lambda _{1}=156\:nm$ (System $1$) and another with light source of wavelength $\lambda _{2}=325\:nm$ (System $2$). Both photolithography systems are otherwise identical. If the minimum feature sizes that can be realized using system$1$ and system$2$ are $L_{min1}$ and …

A lossy transmission line has resistance per unit length $R=0.05\:\Omega/m.$ The line is distortionless and has characteristic impedance of $50\:\Omega.$ The attenuation constant (in $\text{Np/m}$, correct to three decimal places) of the line is ________.

Consider matrix $A=\begin{bmatrix} k & 2k\\ k^{2}-k & k^{2} \end{bmatrix}$ and vector $x=\begin{bmatrix} x_{1}\\ x_{2} \end{bmatrix}.$ The number of distinct real value of $k$ for which the equation $Ax=0$ has infinitely many solutions is _________.

Let $X_{1},\:X_{2},\:X_{3}$ and $X_{4}$ be independent normal random variable with zero mean and unit variance. The probability that $X_{4}$ is the smallest among the four is ________.

Taylor series expansion of $f\left ( x \right )=\int ^{x}_{0}e^{-\left ( \frac{t^{2}}{2} \right )}dt$ around $x=0$ has the form $$f\left ( x \right )={a}_{0}+a_{1}x+a_{2}x^{2}+...$$ The coefficient $a_{2}$ (correct to two decimal places) is equal to ________.

The $\text{ABCD}$ matrix for a two-port network is defined by: $$\begin{bmatrix} V_{1}\\ I_{1} \end{bmatrix}=\begin{bmatrix} A &B \\ C& D \end{bmatrix}\begin{bmatrix} V_{2}\\ -I_{2} \end{bmatrix}$$ The parameter $\text{B}$ for the given two-port network (in ohms, correct to two decimal places) is _________.

The circuit shown in the figure is used to provide regulated voltage $(5 V)$ across the $1\: k\Omega$ resistor. Assume that the Zener diode has a constant reverse breakdown voltage for a current range, starting from a minimum required Zener current, $I_{Z min}=2\:mA$ to its maximum allowable current. The input voltage $V_{I}$ may vary by $5\%$ from …

Let $c\left ( t \right )=A_{c} \cos \left ( 2\pi f_{c}t\right )$ and $m\left ( t \right )=\cos \left ( 2\pi f_{m}t\right )$. It is given that $f_{c}>> 5f_{m}.$ The signal $c\left ( t \right )+m\left ( t \right )$ is applied to the input of a non-linear device, whose output $v_{o}\left ( t \right )$ is related to the input …

Consider a white Gaussian noise process $\text{N(t)}$ with two-sided power spectral density $S_{N}\left ( f \right )=0.5\:W/Hz$ as input to a filter with impulse response $0.5e^{-t^{2}/2}$ (where $t$ is in seconds) resulting in output $Y(t)$. The power in $Y(t)$ in watts is

The state equation and the output equation of a control system are given below: $\dot{x}=\begin{bmatrix} -4 & -1.5\\ 4& 0 \end{bmatrix}x+\begin{bmatrix} 2\\ 0 \end{bmatrix}u,$ $y=\begin{bmatrix} 1.5 & 0.625 \end{bmatrix}x.$ The transfer function representation of the system is

Red (R), Green(G) and Blue (B) Light Emitting Diodes (LEDs) were fabricated using $\text{p-n}$ junctions of three different inorganic semiconductors having different band-gaps. The built-in voltages of red,green and blue diodes are $V_{R}$, $V_{G}$ and $V_{B},$respectively. Assume donor and acceptor doping to be the same ($N_{A}$ and $N_{D},$ …