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

オーディオシステムでは、フィルタ回路はアンプからの増幅されたオーディオ信号を処理し、低周波数の信号成分を強く減衰させます。
反転構成のオペアンプと抵抗R1とR2、およびコンデンサC1を組み合わせた最も単純なフィルタ回路を考えてみましょう。既知の入力信号の結果の出力信号は何ですか?
コンデンサのインピーダンスは、入力電圧の時間領域式から導出された角周波数を使用して計算されます。
周波数領域等価回路は、入力信号を極性形式とインピーダンスZ1およびZ2で表します。インピーダンスZ2は、コンデンサC1と抵抗R2の並列組み合わせに対応します。
キルヒホッフの電流法則とオームの法則をノードに適用すると、理想的なオペアンプのノード方程式が得られます。この式を並べ替えると、入力電圧に対する出力の比率がインピーダンスの負の比率に等しいことを示します。
既知の値と計算された値をこの式に代入することにより、出力電圧は極性形式で決定され、その後、時間領域に変換されます。

オペアンプの ac 回路

オーディオ システム内では、フィルター回路は、アンプから増幅されたオーディオ信号を処理する際に重要な役割を果たします。 その主な機能は、より低い周波数の信号成分を大幅に減衰させ、それによってオーディオ出力を整えられることです。 基本的なフィルター構成に焦点を当てて、この回路の動作を検討します。 この構成には、抵抗 (R1 および R_2) およびコンデンサ (C_1) と結合された反転セットアップで配置されたオペアンプが含まれます。

<img alt="Figure1" src="/files/ftp_upload/15116/15116_PT_Figure_1.svg" style="text-align: center; height: 164px;">

既知の入力信号に直面した場合、課題は、結果として得られる出力信号を決定することにあります。 最初のステップでは、コンデンサのインピーダンスを計算します。これは、入力電圧の時間領域の式から導出される角周波数を使用することによって達成されます。

<img alt="Equation1" src="/files/ftp_upload/15116/15116_PT_Equation_1.svg" style="text-align: center; height: 36px;">

その結果、解析は周波数領域に移行し、入力信号がインピーダンス コンポーネント Z_1 および Z_2 とともに極形式で表されます。 Z_2 は、コンデンサ C_1 と抵抗 R_2 の並列結合に明示的に関係します。 解析の中核は、キルヒホッフの電流の法則とオームの法則を回路内の特定のノードに適用することにあり、それによって理想的なオペアンプのノードFigureを定式化します。 この式を整理すると、入力電圧に対する出力の比はインピーダンスの比に反比例するという重要な洞察が得られます。

<img alt="Equation2" src="/files/ftp_upload/15116/15116_PT_Equation_2.svg" style="text-align: center; height: 36px;">

既知の値と計算された値をこの式に巧みに代入して、出力電圧を極形式で明らかにします。 出力電圧を表す結果は時間領域に変換できるため、入力信号に対するフィルター回路の応答を包括的に理解できます。 解析では、どちらの入力端子にも電流が流れ込まず、入力端子間の電圧がゼロのままであるという原理など、理想的なオペアンプ特性が仮定されることがよくあります。

オペアンプの AC 回路

オーディオシステムでは、フィルター回路はアンプからの増幅されたオーディオ信号を処理し、信号成分を低く減衰させます...

Education

JoVE Core

Electrical Engineering

電気工学

Unit 1

ユニット1

AC Circuit Analysis

交流回路解析

KEY TERMS AND CONCEPTS

主要用語と概念

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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phasors

Phasors for AC Circuit Analysis

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AC Circuit Phasors: Resistor, Inductor, Capacitor

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AC Circuit Rules with Phasor Diagrams

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AC Circuit Response: Impedance and Admittance

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op amp ac circuits

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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key terms and concepts

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

Analyzing an Op Amp Audio Filter | JoVE K12

JoVE Core 電気工学 は、電気回路の基本概念と回路解析テクニックを網羅したアニメーションビデオシリーズです。オペアンプと回路変換および 1 次・ 2 次回路の概念を網羅しています。実験を撮影した実写動画では、設計例や現代社会での応用が含まれており、複雑な概念も分かりやすく学習いただけます。

electrical engineering

Analyzing an Op Amp Audio Filter

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