Each transistor in the Darlington pair (see Fig. below) has h_fe = 100. The overall h_fe of the composite transistor neglecting the leakage current is

The quiescent collector current I_c, of a transistor is increased by changing resistance. As a result

The OP-AMP shown in fig. below is ideal. $$R\, = \,\sqrt {L/C.} $$ The phase angle between V₀ and V_i at $$\omega = 1/\sqrt {LC} $$ is

White Gaussian noise with zero mean and double - sided power spectral density $$\eta /2$$ is the input $$x(t)$$ to a linear system with impulse response $$h(t)$$ $$ = exp\left( { - t/RC} \right)\,\,\,\,\,\,\,\,u\left( t \right)$$. The output is $$y(t)$$ . Evaluate $$E\left[ {x\left( {t + \tau } \right)y\left( t \right)} \right]$$ for $$\tau > 0.$$ (Note: $$u(t)$$ is the unit step function)