Name: reading frequency response on bode plots
Uploaded: 2024-07-08T13:20:02.000Z
Duration: 1 min 26 s
Channel: JoVE

Consider an electrocardiogram unit that utilizes a low-pass filter with a complex network function represented by its magnitude and phase angle.
The decibel logarithmic gain is calculated by multiplying the base ten logarithm of the network function&#39;s magnitude by 20.
Bode plots are semilogarithmic graphs that display the logarithmic gain in decibels and the phase angle in degrees across frequencies.
At lower frequencies, the logarithmic gain and the phase angle approaches zero.
This results in horizontal lines on the Bode plot, known as the low-frequency asymptotes.
At higher frequencies, the calculations for gain and phase angle reflect their dependence on frequency.
They are depicted as straight lines with negative slopes and are known as high-frequency asymptotes.
The low- and high-frequency asymptotes intersect at a corner, also known as the corner frequency.
At this frequency, the asymptotic magnitude deviates by nearly -3 decibels from the exact value, and the phase angle is approximately -45 degrees.
The asymptotic bode plots are good approximations to the actual bode plots.

bodediagram

Bodediagrammen zijn grafische hulpmiddelen die logaritmische schalen gebruiken voor de frequentie op de x-as en de winst in decibel op de y-as. Met deze logaritmische methode kan een breed scala aan frequenties compact worden weergegeven, waardoor de analyse van componenteffecten op het circuitgedrag over een breed frequentiespectrum mogelijk wordt.
Een netwerkfunctie vertegenwoordigt de verhouding tussen de uitvoer van een systeem en de invoer ervan, waarbij de grootte en fasehoek zijn afgeleid van de complexe netwerkfunctie. De logaritmische winst in decibel wordt bepaald door de logaritme met grondtal tien van de omvang van de netwerkfunctie met 20 te vermenigvuldigen. De winst in een Bode-grafiek wordt logaritmisch uitgedrukt. De eenheid van logaritmische versterking is de decibel, ook wel versterking in dB genoemd. Decibels (dB) kwantificeren de versterking, waarbij 1 dB een tiende van een bel is, ter ere van Alexander Graham Bell.
Bode-grafieken, semilogaritmische grafieken, tonen de logaritmische winst in decibel en de fasehoek in graden over een reeks frequenties. Deze grafieken vergemakkelijken het begrip van de frequentierespons van een systeem.
Bij lagere frequenties naderen zowel de logaritmische versterking als de fasehoek nul, waardoor horizontale lijnen op de Bode-grafiek worden gevormd die bekend staan ​​​​als laagfrequente asymptoten. Deze lijnen geven een minimale filterimpact op signalen bij deze frequenties aan. Naarmate de frequentie toeneemt, weerspiegelen de berekeningen van de versterkings- en fasehoek hun frequentieafhankelijkheid. Op de Bode-grafiek verschijnen deze afhankelijkheden als rechte lijnen met negatieve hellingen, de zogenaamde hoogfrequente asymptoten. Deze lijnen laten zien hoe het filter signalen met een hogere frequentie verzwakt. De laag- en hoogfrequente asymptoten kruisen elkaar op de hoekfrequentie. Hier wijkt de asymptotische magnitude ongeveer -3 decibel af van de exacte waarde, wat een significante verandering in de reactie van het filter markeert. Bovendien is de fasehoek bij de hoekfrequentie ongeveer -45 graden.
Asymptotische Bode-grafieken bieden redelijke benaderingen van werkelijke Bode-grafieken, waardoor een vereenvoudigde analyse mogelijk is terwijl een redelijke nauwkeurigheid behouden blijft.

Bodediagram

Consider an electrocardiogram unit that utilizes a low-pass filter with a complex network function represented by its magnitude and phase angle.
The ...

Education

JoVE Core

Electrical Engineering

Elektrotechniek

Unit 1

Frequency Response

Frequentierespons

KEY TERMS AND CONCEPTS

BELANGRIJKE TERMEN EN CONCEPTEN

Bode Plots

reading frequency response on bode plots

Bode plots show how a circuit or system responds across frequency. They use a logarithmic frequency scale on the x-axis and gain in decibels on the y-axis. This format makes it easier to display a wide range of frequencies and to see how circuit parts affect behavior over that range.

A network function gives the ratio of output to input for a system. Its complex form provides both magnitude and phase angle. The logarithmic gain on a Bode plot comes from the magnitude, calculated by multiplying the base-ten logarithm of that magnitude by 20. The gain is measured in decibels, or dB. A decibel is one-tenth of a bel, and the unit honors Alexander Graham Bell.

Because Bode plots are semilogarithmic graphs, they show gain in dB and phase angle in degrees over frequency. This makes the frequency response of a system easier to study. At low frequencies, both gain and phase angle approach zero. These flat regions are called low-frequency asymptotes, and they show that the filter has little effect on the signal there.

As frequency rises, the gain and phase angle change with frequency. On the plot, this appears as straight lines with negative slopes called high-frequency asymptotes. These lines show that the filter attenuates higher-frequency signals. The low- and high-frequency asymptotes meet at the corner frequency. At that point, the asymptotic magnitude is about -3 decibels from the exact value, and the phase angle is about -45 degrees. Asymptotic Bode plots give a reasonable approximation of the actual plot and make analysis simpler while keeping useful accuracy.

Reading Frequency Response on Bode Plots

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bode plots

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key terms and concepts

Learn how Bode plots use decibels, phase angle, and asymptotes to show frequency response, including corner frequency and filter behavior.

Reading Frequency Response on Bode Plots | JoVE K12

JoVE Core Electrical Engineering offers easy-to-understand animated videos that cover fundamental concepts of electric circuits along with circuit analysis techniques. It incorporates first-order and second-order circuits using operational amplifiers and circuit transformation concepts. The inclusion of practical design examples and real-world applications through scientist-in-action videos adds significant educational value, making complex concepts accessible.

electrical engineering

Reading Frequency Response on Bode Plots

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