Name: dc restorer for waveform level shifting
Uploaded: 2024-07-08T13:20:21.000Z
Duration: 1 min 14 s
Channel: JoVE

クランパ回路は、時間とともに変化する入力信号、コンデンサ、およびダイオードで構成されています。出力電圧はダイオードの両端で測定されます。
方形波入力信号の負の半サイクル中、ダイオードは順方向にバイアスされ、ダイオードの両端の電圧はゼロになります。
しかし同時に、コンデンサは入力信号のピーク値まで充電されます。
矩形波の正の半サイクルの間に、ダイオードは逆バイアスされます。ここでは、入力電圧と充電されたコンデンサが結合された電圧源として機能します。
この瞬間、ダイオードの両端の電圧は入力電圧の2倍になります。この回路は、正のクランパとして機能します。
負荷がダイオードの両端に接続されている場合、出力電流は負荷からコンデンサを介して流れます。これにより、出力電圧は時定数RCに従って指数関数的に減少します。 
入力電圧が低下すると、出力電圧がコンデンサに追従して充電されます。入力電圧が再び増加すると、コンデンサは放電し、サイクルが繰り返されます

クランプ回路

クランプ回路は DC リストアとも呼ばれ、整流回路の特殊なバリエーションで、出力をコンデンサではなくダイオードで取る方法が特徴です。この構成は、特に方形波入力の処理において、いくつかの独特な用途に役立ちます。

この回路では、ダイオードの向きによってコンデンサが入力信号の最も負のピークのレベルまで充電されます。この状態に達すると、ダイオードは導通を停止し、コンデンサの電圧を一定レベルに効果的に固定します。このメカニズムにより、出力電圧は元の入力波形になり、コンデンサの両端の電圧 (V_C) に等しい値だけ上昇します。
クランプ回路の主な機能は、波形のベースラインを調整することです。デフォルトでは、波形の最低点が上昇します。ダイオードの極性を変更すると、この効果が逆転し、代わりに波形の最高ピークが 0 ボルトにクランプされます。この機能は、容量結合のあるシステムを介してパルス信号を送信するアプリケーションで特に役立ちます。容量結合は本質的に信号の DC 成分を除去するため、クランプ回路はこの DC レベルを復元する上で重要な役割を果たし、正確なデューティ サイクル変調を容易にします。
ダイオードに負荷抵抗を含めると、回路の動作がさらに複雑になります。このような構成では、出力がグランド レベルを超えるとコンデンサが放電し、出力電圧が微妙に変化します。コンデンサは定常状態で電荷を補充し、信号内の必要な DC 成分を復元して維持する回路の有効性を確保します。

クランパ回路は、時間とともに変化する入力信号、コンデンサ、およびダイオードで構成されています。出力電圧はダイオードの両端で測定されます。
ネガティブな時期に...

Education

JoVE Core

Electrical Engineering

電気工学

Unit 1

ユニット1

Diodes

ダイオード

KEY TERMS AND CONCEPTS

主要用語と概念

Clamper Circuit

dc restorer for waveform level shifting

A clamper circuit, or DC restorer, shifts a waveform up or down by adding a DC level. It is a special form of rectifier circuit. In this setup, the output is taken across the diode instead of across the capacitor.

The circuit works well with square wave inputs and other pulse signals. The diode direction lets the capacitor charge to the most negative peak of the input signal. After that, the diode stops conducting. The capacitor then holds that voltage at a steady value.

As a result, the output becomes the original input waveform shifted by the capacitor voltage, V C. By default, the circuit raises the lowest part of the waveform. If the diode polarity is reversed, the circuit clamps the highest peak at zero volts instead.

This function is useful when signals pass through capacitive coupling. Capacitive coupling removes the DC component of a signal. The clamper circuit restores that DC level, which helps preserve accurate duty cycle modulation. Adding a load resistor across the diode changes the circuit behavior further. In that case, the capacitor can discharge whenever the output rises above ground level. Even then, the capacitor recharges in steady-state conditions and continues to support the restored DC component.

DC Restorer for Waveform Level Shifting

the ideal diode

Ideal Diode I-V Curve and Rectification

An ideal diode is a simple model of a semiconductor diode used to show how current moves through circuits. A diode has two terminals. The anode is positive, and the cathode is negative. In this model, current can flow only in one direction. When a positive voltage is applied to the anode relative to the cathode, the diode is forward-biased. In that state, it conducts current. When the cathode is at a higher potential than the anode, the diode is reverse-biased. It then blocks current and acts...

diode: forward bias

Diode Current in Forward Bias

Diode current in forward bias depends on how the p-type and n-type regions are connected to a battery. When the p-type region is tied to the positive terminal and the n-type region to the negative terminal, the diode is forward-biased. This setup lowers the potential barrier inside the diode and lets current move easily from the p-type side to the n-type side. The current-voltage behavior of a forward-biased diode is described by its I-V characteristics. These characteristics depend on the...

diode: reverse bias

Diode Reverse Current and Breakdown

A diode in reverse bias blocks current flow and widens its depletion region. In this setup, the positive terminal of the power source connects to the n-type material, and the negative terminal connects to the p-type material. The reverse connection also raises the barrier potential, so current stays very small. The small reverse current is called leakage current. It comes mainly from minority charge carriers. At room temperature, once the reverse voltage is above the thermal voltage, the...

zener diodes

Zener Diode Voltage Regulation

Zener diodes are semiconductor devices used to hold voltage steady in reverse bias. In reverse breakdown, current flows into the cathode and makes it positive relative to the anode. This behavior is different from a conventional diode and is the reason Zener diodes are useful in voltage regulation. A Zener diode has a nearly vertical current-voltage, or I-V, curve above a threshold called the knee current. That shape lets it keep a fairly stable voltage over a wide range of currents.

modeling of diode forward characteristics

modeling-of-diode-forward-characteristics

Diode Forward Bias: I-V Curve and Models

Diode forward bias is analyzed with the current-voltage, or I-V, curve and two common circuit models. These models help describe how a diode behaves when current flows in the forward direction. They are useful for electronic circuit design and analysis. The exponential diode model is used when the source voltage rises above 0.5 volts. At that point, the diode current increases exponentially above the saturation current. The I-V curve shows this nonlinear response as the forward voltage...

small-signal diode model

Diode Bias and Small-Signal Response

Diode bias and small-signal response describe how a diode behaves when a steady DC voltage and a tiny changing signal act on the same circuit. The DC bias sets the diode’s operating point, or Q point. Around that point, the diode current and voltage follow an exponential I-V relationship. A small time-varying signal can be added on top of the DC bias to study how the diode responds to small changes. When the signal voltage is much smaller than the thermal voltage, the diode’s behavior can be...

modeling of diode reverse characteristics

modeling-of-diode-reverse-characteristics

Zener Diode Load-Line Modeling

Zener diode load-line modeling shows how a reverse-biased diode sets a steady voltage in a circuit. Zener diodes use reverse breakdown in a controlled way, so they can hold a fixed voltage across their terminals. This makes them useful for voltage regulation. When the reverse voltage rises above the Zener voltage, or VZ, the diode enters the breakdown region. In this region, the current-voltage, or I-V, curve becomes nearly vertical after the knee current, IZ, is reached. That means the...

half wave rectifier

Single-Diode AC to DC Conversion

Single-diode AC to DC conversion uses a half-wave rectifier to change alternating current into a unidirectional voltage. The circuit is simple. It uses one diode in series with a load resistor and an AC power source. The diode controls the current because it allows flow in only one direction. During the positive half-cycles of the AC input, the diode is forward-biased. When the input voltage is greater than the diode threshold, current flows and an output voltage appears across the load...

full wave rectifier

AC to DC Conversion with Full-Wave Rectifiers

A full-wave rectifier converts alternating current, or AC, into direct current, or DC. It is more efficient than a half-wave rectifier. The circuit usually uses a center-tapped transformer, two diodes, and a load resistor. The center-tapped transformer is the key part of the circuit. Its secondary winding is split into two equal voltages with opposite polarities. That split lets the rectifier use both halves of the AC input waveform. During the positive half-cycle of the AC signal, diode D1...

bridge rectifier

AC to DC Conversion with Bridge Diodes

A bridge rectifier converts alternating current (AC) into direct current (DC) using four diodes arranged in a bridge layout. It is used to turn both halves of the AC waveform into a single-direction output. That makes it an important part of many electronics circuits. During the positive half-cycle, diodes D1 and D2 conduct. Current then flows through the load resistor R. At the same time, D3 and D4 are reverse-biased, so they do not conduct. The action switches during the negative half-cycle.

clipper circuit

Dual Diode Wave Clipping

Dual diode wave clipping uses diodes and biasing batteries to reshape an AC signal. A clipper circuit is a wave-shaping device that changes waveform parts without changing the whole signal. It is commonly used in television and radar communication systems to improve waveform modulation in transmitters and receivers. A dual-clipper setup uses two ideal diodes, two biasing batteries, and a resistor connected in parallel. The circuit works by responding to the phase of the input AC signal. The...

clamper circuit

A clamper circuit, or DC restorer, shifts a waveform up or down by adding a DC level. It is a special form of rectifier circuit. In this setup, the output is taken across the diode instead of across the capacitor. The circuit works well with square wave inputs and other pulse signals. The diode direction lets the capacitor charge to the most negative peak of the input signal. After that, the diode stops conducting. The capacitor then holds that voltage at a steady value. As a result, the...

voltage doubler circuit

How a Voltage Doubler Raises AC Output

A voltage doubler circuit raises the output voltage by using a clamping section and a rectifier section. The clamping section includes a capacitor, C1, and a diode, D1. The rectifier section includes a second diode, D2, and a capacitor, C2. The circuit starts working when a sinusoidal input signal enters the clamping section. Under ideal conditions, this stage clamps the positive peaks at zero volts. It also lets the negative peak reach a magnitude that is twice the input amplitude. That...

schottky barrier diode

Fast Switching in Schottky Diodes

Schottky barrier diodes use a metal-semiconductor junction to control current flow. They are built by combining a metal layer with a moderately doped n-type semiconductor. This contact creates the Schottky barrier, which gives the diode its one-way current behavior. When the metal touches the semiconductor, charge transfer occurs. The Fermi levels of the two materials align, and a depletion region forms near the contact area. In an n-type semiconductor, this region contains uncompensated...

key terms and concepts

Learn how a clamper circuit, or DC restorer, shifts waveform levels, restores DC after capacitive coupling, and clamps peaks with a diode and capacitor.

DC Restorer for Waveform Level Shifting | 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

DC Restorer for Waveform Level Shifting

Description

Transcript

Tags