Active Notch RC-Filters of the Fourth Order with an Adjustable Delay Band and Uneven Amplitude–Frequency Response

—Potential structural schemes of notch filters (NFs) of the fourth order are considered. Equations for the coefficients of their transfer functions are given. A graphical interpretation of the parameters of the amplitude–frequency response (AFR) of the proposed NF is presented. An implementation example of the fourth-order NF is studied and simulated in the Micro-Cap 12 environment, confirming the possibility of independent adjustment of AFR unevenness in the passband and in the stopband.