a) Figure Q3(a) shows an active filter circuit that is commonly used in commercial audio crossover applications Sketch magnitude gain (dB) versus frequency of the filter in Figure Q3(a). (4 marks) (ii) Suggest modification of the circuit in Figure Q3(a) to be a 2 kHz second-order low-pass, Butterworth active filter while maintaining the capacitance value. Sketch the magnitude gain (dB) versus frequency of the new filter. Given Table Q3(a) as a reference for the Butterworth response. (6 marks) 19.9 k92 Vin Ho 10 nF 10 nF 19.9k2 Vout 10 24 k2 10 k22 Figure Q3(a) 2nd stage Order R3/R4 1 2 3 4 Table Q3(a): Values for the Butterworth response Roll-off Ist stage dB/decade Poles DF R/R Poles DF -20 1 Optional -40 2 1.414 0.586 -60 2 1.00 1.00 1 1.00 -80 2 1.848 0.152 2 0.765 1.00 1.235