Other Oscillators Topologies — Lesson 3

It This lesson covers the various oscillator topologies including the negative resistance-based oscillator, Colpitt oscillator, Hartley oscillator, and ring oscillator. It explains the concept of phase noise and how it is quantified in an oscillator. It further explains the concept of frequency synthesis in a radio system, emphasizing the need for a pure frequency, agility, and accuracy. For instance, in a cell phone system, the oscillator must be able to rapidly switch channels as instructed by the base station, and it must do so with high precision.

Video Highlights

04:02 - Colpitts oscillator, its structure, and how it works
14:41 - Ring oscillator, its structure, and how it works
30:34 - Loop gain, jitter and phase noise
50:00 - Comparison between the LC circuit and the RC circuit
57:11 - Advantages of quartz crystals in terms of pure frequency and accuracy

Key Takeaways

- Phase noise is the noise that remains after cutting out the noise in the amplitude in an oscillator.
- Different oscillator topologies have different characteristics and uses.
- In a radio system, the oscillator must have a pure frequency, agility and accuracy.
- Quartz crystals are unbeatable in terms of providing a pure frequency and accuracy, while voltage control oscillators offer agility.
- In a ring oscillator, each gate has a delay, which contributes to the overall oscillation frequency.