The filter shown in figure 1 uses an RC feedback network and the signals of the tuned frequency are rejected.
Formula 1
Notch filter frequency:
f = √3 / (2 x π x R x C)
Where:
f is the frequency in hertz (Hz)
R is the resistance in ohm (Ω)
C is the capacitance in farads (F)
π is 3.1416
√3 = 1.7320
