GATE EC 2018 Question Paper (10-Feb-2018) (Shift 1)

Two identical NMOS transistors M₁ and M₂ are connected as shown below. The circuit is used as an amplifier with the input connected between G and S terminals and the output taken between D and S terminals. V${}_{bias}$ and V${}_D$ are so adjusted that both transistors are in saturation. The transconductance of this combination is defined as {_} = {{{_}}}{{{_{}}_ }} while the output resistance is {_} = {{{_{}}_ }}{{{_}}}, where i${}_D$ is the current flowing into the drain of M₂. Let g${}_{m1}$, g${}_{m2}$ be the transconductances and r₀₁, r₀₂ be the output resistances of transistors M₁ and M₂, respectively.



Which of the following statements about estimates for g${}_m$ and r₀ is correct?

In the circuit shown below, the op-amp is ideal and the Zener voltage of the diode is 2.5 volts. At the input, unit step voltage is applied, i.e. V${}_{IN}$ (t) = u(t) Volts. Also, at t = 0, the voltage across each of the capacitors is zero.



The time 't', in milliseconds, at which the output voltage V${}_{OUT}$ crosses −10 V is:

A good transimpedance amplifier has

Let the input be u and the output is y of a system, and the other parameters are real constants. Identify which among the following systems is not a linear system:

The Nyquist stability criterion and the Routh criterion both are powerful analysis tools for determining the stability of feedback controllers. Identify which of the following statements is FALSE: