Diode Clipping and Clamping Circuits - 1.7

Key Concepts

• Clipping: Removal of Amplitudes: Cuts off parts of the waveform.

• Clamping: DC Level Shift: Shifts the entire waveform's DC reference.

• Diode Bias: Allows for adjustable clipping/clamping levels.

• Capacitor in Clampers: Essential for storing the DC voltage that causes the shift.

• RC Time Constant (for Clampers): Must be long enough to maintain the charge and thus the DC shift.

• Series vs. Parallel Clippers: How the diode's position affects operation.

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• Examples

• Clipper Examples:

• Audio Overdrive/Distortion: Simple clippers can be used to intentionally distort audio signals by flattening peaks.

• Voltage Regulation (Crude): Can provide a rough form of voltage limiting.

• Square Wave Generation (from Sine Wave): By clipping both positive and negative peaks of a large sine wave, a near-square wave can be generated.

• Input Protection: Protecting op-amp inputs or other sensitive circuits from excessive voltage swings.

• Clamper Examples:

• Video Signal Processing: Restoring the DC level in analog video signals to ensure proper display of black and white levels.

• Voltage Multipliers: The first stage of a voltage doubler circuit is a clamper.

• DC Restoration in AC-Coupled Circuits: If a signal passes through a capacitor (AC coupling), its DC component is lost. A clamper can restore a desired DC level.

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• Flashcards

• Term: Clipper

• Definition: A circuit that limits/removes portions of a waveform above or below a threshold.

• Term: Clamper

• Definition: A circuit that shifts the DC level of an AC waveform without changing its shape.

• Term: Unbiased Clipper

• Definition: Clips at diode's $V\_D$ (e.g., $0.7 \text{ V}$).

• Term: Biased Clipper

• Definition: Clips at an external DC voltage plus/minus $V\_D$.

• Term: Positive Clamper

• Definition: Shifts waveform upward, clamping negative peak (or another point) to a higher DC level.

• Term: Capacitor in Clamper

• Definition: Charges to a DC voltage, which then shifts the entire waveform.

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• Memory Aids

• "CliPPer = Cut Portions": Remember that clippers cut or flatten parts of the waveform.

• "ClaMPer = Make Peak": Clampers force one peak (or another point) to a specific DC level.

• "Clipper, No Capacitor; Clamper, Capacitor\!": A simple way to distinguish their main components.

• "Diode Points Up = Positive Shift (Clamper); Diode Points Down = Negative Shift (Clamper)": A visual mnemonic for clamper orientation.

• "Series Shuts Off; Parallel Shorts Out": For series clippers, the diode turns off to block, for parallel clippers, it turns on to shunt the signal.

• This video provides a basic introduction to how clamper circuits function to shift a waveform above or below a certain reference voltage: Clamper Circuits.

• http://googleusercontent.com/youtube_content/5

Examples & Applications

Memory Aids

Interactive tools to help you remember key concepts

Glossary