from scipy.signal import freqs, iirfilter b, a = iirfilter(4, [1, 10], 1, 60, analog=True, ftype='cheby1') w, h = freqs(b, a, worN=np.logspace(-1, 2, 1000)) import matplotlib.pyplot as plt plt.semilogx(w, 20 * np.log10(abs(h))) plt.xlabel('Frequency') plt.ylabel('Amplitude response [dB]') plt.grid() plt.show()