Why 20db per decade

The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Ask Question. Asked 3 years, 6 months ago. Active 3 years, 6 months ago. Viewed 9k times. Bee Bee 6 6 silver badges 15 15 bronze badges. There is an academic technique to draw an approximate Bode plot based on the poles and zeros.

In general, the slope of the simple low-pass filter response is 20dB per decade if there is only one reactive component. Google techniques for drawing the Bode Plot. Just go to Google. As soon as your browser navigates to the search results, your screen will be filled with Os, leaping in true Zergling-fashion toward elements on the page….

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Skip to content Users questions. While that is possible, it is unlikely. What decade is ? What defines a century? A century is a period of years. Centuries are numbered ordinally in English and many other languages. The word century comes from the Latin centum, meaning one hundred. Century is sometimes abbreviated as c. What is a period of 10 years called? A decade is a period of 10 years.

What is meant by dB? Definition and examples. The decibel dB is a logarithmic unit used to measure sound level. Bode Plots show both of these characteristics on a shared frequency scale making a comparison between the gain of the filter and the phase shift simple and accurate. Frequency is plotted on the horizontal axis using a logarithmic scale, on which every equal division represents ten times the frequency scale of the previous division, this allows for a much wider range of frequency to be displayed on the graph than would be possible using a simple linear scale.

Because the frequency scale increases in "Decades" multiples of x10 it is also a convenient way to show the slope of the gain graph, which can be said to fall at 20dB per decade. The vertical axis of the gain graph is marked off in equal divisions, but uses a logarithmic unit, the decibel dB to show the gain, which with simple passive filters is always unity, or a gain ratio of 1 or less, a gain of 1 corresponds to 0dB on the logarithimic Decibel scale.

The dB units therefore have negative values indicating that the output of the filter is always less than the input, i. A typical Bode plot for a low pass filter is shown in Fig 8. Note the point called the corner frequency.