Name: analyzing an op amp audio filter
Uploaded: 2024-04-11T12:48:50.000Z
Duration: 1 min 18 s
Channel: JoVE

W systemie audio obwód filtra przetwarza wzmocniony sygnał audio ze wzmacniacza, silnie tłumiąc składowe sygnału o niskich częstotliwościach.
Rozważmy najprostszy obwód filtra składający się ze wzmacniacza operacyjnego w konfiguracji odwracającej sprzężonego z rezystorami R1 i R2 oraz kondensatorem C1. Jaki jest wynikowy sygnał wyjściowy dla znanego sygnału wejściowego?
Impedancję kondensatora oblicza się przy użyciu częstotliwości kątowej wyprowadzonej z wyrażenia w dziedzinie czasu dla napięcia wejściowego.
Obwód równoważny w dziedzinie częstotliwości reprezentuje sygnał wejściowy w postaci biegunowej i impedancji Z1 i Z2. Impedancja Z2 odpowiada równoległej kombinacji kondensatora C1 i rezystora R2.
Zastosowanie obecnego prawa Kirchoffa i prawa Ohma w węźle daje równanie węzłowe dla idealnego wzmacniacza operacyjnego. Równanie to, po przestawieniu, wskazuje, że stosunek napięcia wyjściowego do napięcia wejściowego jest równy ujemnemu stosunkowi impedancji.
Podstawiając znane i obliczone wartości do tego równania, napięcie wyjściowe jest określane w postaci biegunowej, która jest następnie przekształcana w dziedzinę czasu.

obwody prądu przemiennego wzmacniacza operacyjnego

W systemie audio obwód filtra odgrywa kluczową rolę w przetwarzaniu wzmocnionego sygnału audio ze wzmacniacza. Jego podstawową funkcją jest znaczne tłumienie składowych sygnału o niższych częstotliwościach, a tym samym kształtowanie wyjścia audio. Zbadano działanie tego obwodu, koncentrując się na podstawowej konfiguracji filtra. Konfiguracja ta obejmuje wzmacniacz operacyjny w układzie odwracającym, połączony z rezystorami (R1 i R2) i kondensatorem (C1).

<img alt="Figure1" src="/files/ftp_upload/15116/15116_PT_Figure_1.svg" style="text-align: center; height: 164px;" />

Gdy znany jest sygnał wejściowy, wyzwaniem jest określenie wynikowego sygnału wyjściowego. Pierwszy krok polega na obliczeniu impedancji kondensatora, co osiąga się poprzez wykorzystanie częstotliwości kątowej pochodzącej z wyrażenia napięcia wejściowego w dziedzinie czasu.

<img alt="Equation1" src="/files/ftp_upload/15116/15116_PT_Equation_1.svg" style="text-align: center; height: 36px;" />

W rezultacie analiza przechodzi do dziedziny częstotliwości, gdzie sygnał wejściowy jest reprezentowany w postaci biegunowej wraz ze składowymi impedancji Z1 i Z2. Z2 odnosi się wyraźnie do równoległego połączenia kondensatora C1 i rezystora R2. Istota analizy opiera się na zastosowaniu prądowego prawa Kirchhoffa i prawa Ohma w konkretnym węźle obwodu, formułując w ten sposób równanie węzłowe dla idealnego wzmacniacza operacyjnego. To równanie, po przekształceniu, ujawnia kluczowy spostrzeżenie: stosunek napięcia wyjściowego do napięcia wejściowego jest odwrotnie proporcjonalny do stosunku impedancji.

<img alt="Equation2" src="/files/ftp_upload/15116/15116_PT_Equation_2.svg" style="text-align: center; height: 36px;" />

Znane i obliczone wartości są umiejętnie podstawiane do tego równania, aby odsłonić napięcie wyjściowe w postaci polarnej. Wynik reprezentujący napięcie wyjściowe można następnie przekształcić w dziedzinę czasu, zapewniając kompleksowe zrozumienie reakcji obwodu filtra na sygnał wejściowy. Do analizy często zakłada się idealne właściwości wzmacniacza operacyjnego, w tym zasadę, że prąd nie wpływa do żadnego z jego zacisków wejściowych i że napięcie na jego zaciskach wejściowych pozostaje zerowe.

Obwody prądu przemiennego wzmacniacza operacyjnego

W systemie audio obwód filtra przetwarza wzmocniony sygnał audio ze wzmacniacza, silnie tłumiąc składowe sygnału o niskim ...

Education

JoVE Core

Electrical Engineering

Elektrotechnika

Unit 1

Jednostka 1

AC Circuit Analysis

Analiza obwodów prądu przemiennego

KEY TERMS AND CONCEPTS

Kluczowe terminy i pojęcia

Op Amp AC Circuits

analyzing an op amp audio filter

An op amp audio filter shapes an amplified sound signal by strongly reducing the lower-frequency parts. In this circuit, the focus is on a basic filter setup used after an amplifier in an audio system. The filter uses an operational amplifier in an inverting arrangement with resistors R1 and R2 and a capacitor C1.

The analysis starts with a known input signal and asks for the output signal. To solve it, the capacitor impedance is found first. That requires the angular frequency from the time-domain form of the input voltage, so the work moves into the frequency domain.

In the frequency domain, the input signal is written in polar form. The impedances Z1 and Z2 are then used, with Z2 representing the parallel combination of capacitor C1 and resistor R2. At the same time, the ideal op amp assumptions are used. No current enters either input terminal, and the voltage across the input terminals is zero.

The final step is applying Kirchhoff's current law and Ohm's law at one node in the circuit. This creates a nodal equation for the ideal op amp. When that equation is rearranged, the output-to-input voltage ratio is shown to be inversely proportional to the impedance ratio. The known values are then substituted to find the output voltage in polar form, and that result can be converted back to the time domain for a full description of the filter response.

Analyzing an Op Amp Audio Filter

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An op amp audio filter shapes an amplified sound signal by strongly reducing the lower-frequency parts. In this circuit, the focus is on a basic filter setup used after an amplifier in an audio system. The filter uses an operational amplifier in an inverting arrangement with resistors R1 and R2 and a capacitor C1. The analysis starts with a known input signal and asks for the output signal. To solve it, the capacitor impedance is found first. That requires the angular frequency from the...

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Learn how an op amp audio filter reduces low-frequency signals. Follow impedance, nodal analysis, and polar-to-time-domain output calculations.

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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

Analyzing an Op Amp Audio Filter

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