Clampers (DC restorers): Which statements correctly describe what a clamper circuit does to a waveform?
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AIt adds or subtracts a DC level to reposition the waveform baseline
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BIt does not change the waveform shape (ideally only shifts it vertically)
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CIt amplifies the waveform amplitude
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DBoth (a) and (b) are correct
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EBoth (b) and (c) are correct
Answer
Correct Answer: Both (a) and (b) are correct
Explanation
Introduction / Context:Clampers are widely used for baseline restoration, level shifting, and AC-coupled signal processing. They translate an entire waveform up or down without altering its peak-to-peak value (ideally), enabling diode detectors and CRT/ADC front-ends to operate within range.
Given Data / Assumptions:
- Ideal diode and large capacitor so that steady-state clamping is achieved.
- Load resistance much larger than the source resistance to minimize droop.
Concept / Approach:
A clamper adds a DC component by charging its capacitor on one half-cycle and then referencing subsequent cycles to a new DC level through the diode action. The instantaneous shape is preserved except for small ripple due to the capacitor discharge; the peak-to-peak amplitude remains the same.
Step-by-Step Solution:
During the charging interval, the diode conducts and sets a reference level.On the opposite half-cycle, the diode is off and the capacitor holds the charge, shifting the entire waveform by a DC amount.Thus, only the DC level changes; the AC shape is essentially unchanged.Verification / Alternative check:
Measure the output: the difference between maximum and minimum remains the input peak-to-peak value, confirming that no amplification occurs.
Why Other Options Are Wrong:
- Amplification is not a function of a clamper; it is a passive level shifter.
Common Pitfalls:
- Confusing clampers with clippers (which alter shape by limiting peaks).
- Neglecting capacitor droop under finite load, which slightly distorts the ideal behavior.
Final Answer:
Both (a) and (b) are correct.