---
title: "Short note: Diode clamper circuit"
subject: "Basic Electronics Engineering"
chapter: 2
key: "semester_2/basic_electronics_engineering:short-note-diode-clamper"
source: https://www.bctengineer.com/q/semester_2/basic_electronics_engineering/short-note-diode-clamper
site: BCT Engineering
---

# Short note: Diode clamper circuit

Basic Electronics Engineering · Chapter 2: Diodes

- Asked in: 2068 Magh, 4 marks
- Video: [Introduction to Clampers](https://www.youtube.com/watch?v=LA7c7jenkd0) — Neso Academy
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_2/basic_electronics_engineering/short-note-diode-clamper
- Whole chapter: https://www.bctengineer.com/md/semester_2/basic_electronics_engineering/chapter-2

## Question

Write a short note on diode clamper circuit.

## Short answer

A diode clamper (DC restorer) shifts an AC waveform’s DC level without distorting it, using a capacitor, diode, and large time constant RC. A positive clamper shifts the signal upward so it swings from 0 to +2Vm; a negative clamper shifts downward. Used in TV receivers, voltage multipliers, and level shifters.

## Answer

A **diode clamper** (dc restorer) is a circuit that shifts the dc level of an ac signal up or down without changing its shape. It consists of a capacitor, a diode, a resistor and sometimes a dc battery. It works because the capacitor stores a dc voltage through the diode and the time constant RC is made much larger than the signal period, so the stored voltage does not leak away.

#### Types
- **Positive clamper:** shifts the waveform upward. The negative peak is clamped at 0 V (or at +V if a battery is used).
- **Negative clamper:** shifts the waveform downward. The positive peak is clamped at 0 V.
- **Biased clamper:** a dc battery in series with the diode moves the clamp level to ±V.

#### Positive clamper working
```text
 Vin o---| |---+---o Vout
          C    |
              D (anode to ground)   R across output
 GND o---------+---o
```
- During the first negative half cycle, the diode conducts and charges the capacitor to Vm.
- Afterwards, the capacitor works like a battery of Vm in series with the source, so Vout = Vin + Vm.
- The output swings from 0 to 2Vm.

```text
 Vin  /\  /\        Vout  /\  /\ 2Vm
 ----/--\/--\-- 0       --/  \/  \--- 0
```

**Uses:** TV receivers (restoring the dc level of the video signal), radar, voltage multipliers, and level shifting in test circuits.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Why does the clamper keep its dc shift?
   A. Capacitor stores a dc voltage through the diode and RC is much longer than the period
   B. The diode always conducts
   C. The resistor is small
   D. The battery supplies it
   Answer: A. A large RC prevents the stored voltage from leaking away. (Key point: Principle)

2. For a positive clamper, what is the output swing?
   A. -Vm to +Vm
   B. -2Vm to 0
   C. 0 to Vm
   D. 0 to 2Vm
   Answer: D. Vout = Vin + Vm. (Key point: Positive clamper output)

3. What does a battery in series with the diode do?
   A. Moves the clamp level to ±V
   B. Removes the capacitor
   C. Doubles frequency
   D. Clips the peaks
   Answer: A. The bias changes the clamping level. (Key point: Biased clamper)

## Related in Basic Electronics Engineering

- [Diode clamper circuit operation](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Adiode-clamper-operation) — Basic Electronics Engineering, chapter 2
- [Short note: Graphical analysis of diode circuit](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Adiode-graphical-analysis) — Basic Electronics Engineering, chapter 2
- [What are clipper and clamper circuits](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Aclipper-clamper-define) — Basic Electronics Engineering, chapter 2
- [Clamper adding +5 V DC level](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Aclamper-adds-5v) — Basic Electronics Engineering, chapter 2
- [Design clamper for given waveforms](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Aclamper-20v-to-30v) — Basic Electronics Engineering, chapter 2

## Related in other subjects

- [Clamper circuit output waveform](https://www.bctengineer.com/question.md?key=semester_1%2Ffundamental_of_electrical_and_electronics_engineering%3Aclamper-output-waveform) — Fundamental of Electrical and Electronics Engineering, chapter 4
- [Diode circuit current, eta 1.74](https://www.bctengineer.com/question.md?key=semester_3%2Felectronics_devices_and_circuit%3Adiode-current-eta-1p74) — Electronics Devices and Circuit, chapter 1, asked 4×
- [Diode circuit current, eta 1.74, 10 V](https://www.bctengineer.com/question.md?key=semester_3%2Felectronics_devices_and_circuit%3Adiode-current-eta-1p74-10v) — Electronics Devices and Circuit, chapter 1, asked 4×
- [Diode circuit current, eta 1.74, 6 V](https://www.bctengineer.com/question.md?key=semester_3%2Felectronics_devices_and_circuit%3Adiode-current-eta-1p74-6v) — Electronics Devices and Circuit, chapter 1, asked 4×