The transfer function of 4 points MA IIR filter is
H(z)=14[1−z−41−z−1]
H(z)=14[1−z−41−z−4]
H(z)=14[1−z−2−z−41−z−1]
H(z)=14[1−z−81−z−1]
H(z)=14[1−z−41−z−1]
H(z)=14[1−z−41−z−4]
H(z)=14[1−z−2−z−41−z−1]
H(z)=14[1−z−81−z−1]