GATE EC 2026 Question Paper (15-Feb-2026) (Shift 1)

Consider the two-port network as shown in the Figure.
Which of the following options provides the correct set of values of A, B, C and D parameters?

A complex load (in $\Omega$) is represented as ${\Gamma }_L=0.5\angle 30^{\circ }$ on the Smith chart.
A co-axial cable with a characteristic impedance of 50 $\Omega$ is connected to the load.
The new input impedance of the load now moves to a diametrically opposite point on the same $\Gamma$ circle on the Smith chart.
Which option is the nearest input impedance of the cable connected load (in $\Omega$)?

A circuit using an ideal OP-AMP is shown in the Figure.
Which of the following options gives the correct value of the current $I_X$?

Consider an LED based on a direct bandgap semiconductor material with energy bandgap 1.3 eV.
Given: Plank's constant, $h=6.63\times 10^{-34}\text{ J s}$ and speed of light in free space is $3\times 10^8{\text{ m s}}^{-1}$.
In which of the following wavelength ranges the LED will NOT emit?

Let the relevant bandwidth ($B$) of a digital communication system be 1 MHz and $kT=-174\text{ dBm/Hz}$, where $k$ is Boltzmann's constant and '$T$ ' is equivalent noise temperature of the receiver. The power ($S$) of signal received through an additive Gaussian channel is $-80\text{ dBm}$.
Which of the following options is/are TRUE about Shannon capacity ($C$) of the channel?