This educational video delves into the fundamental concept of the -20dB/decade rolloff characteristic of filters, a critical aspect of both analog and digital signal processing. The video begins by revisiting the basics of filters and their phase responses, specifically addressing the -45degree/decade phase estimation. The classic RC lowpass filter serves as the primary example to illustrate these concepts. The video provides a step-by-step explanation of the filter's transfer function, and how it transitions into the frequency domain. The video demonstrates how to calculate the magnitude and phase of the filter's response. By exploring the behavior of the RC filter at various frequencies and converting the results into decibels, the video explains the origin of the -20dB/decade rolloff and the -6dB/octave relationship. Timestamps: 0:00 – Introduction 0:31 – RC low pass filter 1:58 – Complex numbers à magnitude and phase 3:34 – Magnitude and phase of RC filter 5:34 – -20dB/decade 6:47 – Phase response: -45°/decade 7:32 – -6dB/octave 8:22 - Outro