Positive and Negative Clamper Circuits: A Detailed Explanation

Clamper vs. Clamp:
- Clamper: Adds a DC voltage to the signal
- Clamp: Protects sensitive circuits by limiting voltage
Positive Clamper:
- Operation:
  - Shifts the AC reference level up to a DC level
  - AC signal centered on a positive DC level
- Effect:
  - Each point on the sine wave is shifted upward
  - Positive peak: \(2V_p\), Negative peak: \(0\) V

Working Principle:
- Capacitor Charging:
  - Initially uncharged capacitor
  - On the first negative half-cycle, the diode conducts
  - Capacitor charges to \(V_p\)
- Stiff Clamper:
  - \(R_L C > 100T\) ensures the capacitor remains charged
  - Acts like a battery of \(V_p\) volts
  - Produces a positively clamped signal
- Real-World Consideration:
  - Diode drop of 0.7 V during conduction
  - Output reference level slightly below zero at \(-0.7\) V

Negative Clamper:
- Operation:
  - Diode reversed from the positive clamper configuration
  - Capacitor voltage reverses, resulting in a negative clamping effect
  - Sine wave shifts downward, creating a negative clamping
- Clamping Level:
  - Positive peaks have a reference level of \(+0.7\) V instead of 0 V
Diode Orientation as Memory Aid:
- Diode points in the direction of the waveform shift
- Negative Clamper: Diode points down, waveform shifts down
- Positive Clamper: Diode points up, waveform shifts up

Applications:
- Widely used in television receivers to adjust video signal reference levels
- Also found in radar and communication circuits
Imperfections:
- Less-than-perfect clamping due to the diode’s barrier potential
- Solutions involving op amps will be discussed later to achieve near-perfect clamping