The transfer function of a real system, $H(s)$, is given as:
$H\left ( s \right ) = \dfrac{As + B}{S^{2} + Cs + D}$
where $\text{A, B, C}$ and $D$ are positive constants. This system cannot operate as
- low pass filter.
- high pass filter.
- band pass filter.
- an integrator.