Sensitivity of classical filter transfer functions

We present here the sensitivity of classical filter transfer functions that are polynomial approximations to the ideal brick-wall magnitude response. The transfer function is decomposed into the part corresponding to the passband ripple parameter and the approximating polynomial. It is shown that the sensitivity has a complementary transfer function response. With these sensitivity relations, it is possible to relate filter parameter variations to any part of the circuit implementing the transfer function. Examples are submitted and discussed to show the usefulness of these new results in providing a more thorough assessment of filter performance potential and limitations.