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0x_oscillators.md

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8. Transmitters

TODO: Complete this chpater

Definitions

  • Oscillator are circuits that continually generates a signal at a given frequency.

Notes

For oscillation to occur certain conditions must be met:

  • transistor must have enough gain (amplification)
    • to overcome feedback losses
  • feedback must be in the correct phase
    • must be positive feedback

To obtain the correct feedback to ensure oscillation:

  • Mutual inductance (transformer action) between the coils in the input and output circuits
  • Feedback circuit from output to input
  • Tapped coil. Part of the coil is in the input circuit and part of the coil is in the output circuit.

TODO: Clapp oscillator - it came out in the exams

Types of oscillator circuits

Colpitts Oscillator
  • Circuit of a Colpitts Oscillator, using a crystal:

  • Circuit of a Colpitts Oscillator, using a series LC network: