Following fig. shows the block diagram representation of control system. The system in block A has an impulse response h(t ) = e^−t u(t ). The system in block B has an impulse response h(t ) = e^−2t u(t ). The block 'K' amplifies its inputs by a factor k. For the overall system with input x(t) and output y(t). (a) Find the transfer function $$\frac{y\left(s\right)}{x\left(s\right)}$$ when k =1.
(b) Find the impulse response when k = 0.
(c) Find the values of k for which the system becomes unstable.

For the circuit shown in the figure, choose state variables as $${x_{1,}}{x_{2,}}{x_3}$$ to be $${i_{L1}}\left( t \right),{v_{c2}}\left( t \right),{i_{L3}}\left( t \right)$$

Wriote the state equations

$$$\left[ {\matrix{ {\mathop {{x_1}}\limits^ \bullet } \cr {\mathop {{x_2}}\limits^ \bullet } \cr {\mathop {{x_3}}\limits^ \bullet } \cr } } \right] = A\left[ {\matrix{ {{x_1}} \cr {{x_2}} \cr {{x_3}} \cr } } \right] + B\left[ {e\left( t \right)} \right]$$$

For the NMOS logic gate shown in figure, the logic function implemented is

The gate delay of an NMOS inverter is dominated by charge time rather than discharge time because