Figure Q3(a) shows an active filter circuit that is commonly used in commercial audio crossover applications. (i) 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. 19.9 Vin H HH 10 nF 10 nF Vout 19.9 w 10 24 10 Figure Q3(a) Table Q3(a): Values for the Butterworth response (6 marks) Roll-off 1st stage 2nd stage Order dB/decade Poles DF R1/R2 Poles DF R3 R4 1 -20 1 Optional 2 -40 2 1.414 0.586 3 -60 2 1.00 1.00 1 1.00 1.00 4 -80 2 1.848 0.152 2 0.765 1.235