Example image of eyePlorer eyePlorer map for 'Active filter': Amplifier Analog signal Buffer amplifier Electronic filter Passivity (engineering) Operational amplifier Transistor Vacuum tube Q factor Electronic filter topology Sallen–Key topology State variable filter High-pass filter Low-pass filter Band-pass filter Band-stop filter Impedance Square wave Bessel filter Butterworth filter Chebyshev filter Elliptic filter Gyrator Network synthesis filters Biquad filter The Art of Electronics Filter (signal processing) Integrated circuit design Signal processing Voltage-controlled filter Roll-off Linear filter Integrated circuit Passive analogue filter development