A requirement exists to design an IIR digital highpass filter with a Butterworth characteristic to meet the following specifications: Passband edge frequency Stopband Passband ripple Stopband attenuation Sampling frequency 3.75 kHz 0-937.5 Hz 3 dB 25 dB 15 kHz a) Determine the passband and stopband edge frequencies for a suitable analogue prototype lowpass filter. Your answer must include details of the basic concepts of how the prototype lowpass filter is obtained from the filter specifications. (6 marks) b) Determine the order, N, of the prototype lowpass filter. (5 marks) c) Determine the z-domain transfer function and, hence, the coefficients of the IIR filter using the BZT (Bilinear z-transform) method. (14 marks)