CLIPPER CIRCUITS

Aim

To simulate and analyze the behavior of positive and negative clippers, study their output waveforms, measure performance parameters, and verify results against theoretical expectations.

Principle:

The experiment uses diodes' unidirectional conduction property to clip parts of a 5V peak sine wave. By adjusting diode orientation and reference voltage, specific signal portions (positive or negative) are clipped. The reference voltage sets the clipping level, while series and parallel configurations influence the signal's behavior and waveform characteristics.

Procedure

Step 1: Circuit Design in LT Spice

1) Open LT Spice:

- Launch the software and create a new schematic.

2) Choose Components:

- Select components for the simulation:
  - AC voltage source (V1)
  - Diode (D1)
  - Resistor (R1)
  - Optional: DC bias voltage source (V{bias}) for biased clipping.

3) Build Circuits:

- Positive Clipper:
  - Connect the anode of the diode (D1) to the AC voltage source (V1).
  - Connect the cathode to the output node (V{out}).
  - Place a resistor (R1) between the output node and ground.
  - For biased clipping, add a DC voltage source (V{bias}) in series with the diode.
- Negative Clipper:
  - Reverse the diode orientation.
  - Connect the cathode of the diode to the AC voltage source (V1).
  - Connect the anode to the output node (V{out}) with a resistor (R1) to ground.
  - Include a DC voltage source (V{bias}) in series with the diode for biased clipping.

Step 2: Input Parameters

1) Set the AC voltage source (V1) to a sine wave:

- Peak amplitude: 230v
- Frequency: 50Hz

2) Adjust the DC bias voltage (V{bias}) as needed (e.g., 5v, 10v, etc.).

Step 3: Simulation Setup

1) Select Analysis Type:

- Choose a transient analysis to observe time-domain waveforms.
- Configure the simulation with the command.

. trans 0 100ms.

2) Add Probes:

- Place voltage probes at the input (V{in}) and output (V{out}) to visualize the waveforms.

Step 4: Run Simulations

1) Perform separate simulations for:

- Positive clipper.
- Negative clipper.

2) Capture the following observations:

- Clipped portions of the waveform.
- Clipping thresholds based on diode forward voltage (Vf) and bias voltage (V{bias}).

Repeat simulations for different temperatures (25∘C, 50∘C, 75∘) to study

temperature effects.

Step 5: Data Recording

1) Record waveforms and clipping points for each configuration.

2) Note changes in the clipping behavior due to temperature variations.

Circuit

Positive Clipper

Negative Clipper

Nature of the graph

Positive Clipper

Negative Clipper

Result

1) The positive clipper successfully clipped the input waveform, removing the

portion above the reference voltage level.

2) The clipping level was consistent with the theoretical value determined by the

diode's forward voltage and reference voltage.

Conclusion

The simulation verified the operation of the positive clipper:

The circuit effectively removed the positive peaks above the reference voltage.
The observed waveforms matched theoretical predictions, demonstrating the functionality of a positive clipper.

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