Oscillator Design - Part I — Lesson 1

This lesson covers the design and functioning of oscillators, specifically focusing on mixer design, oscillator design, and the performance parameters important for oscillator design. It explains the concept of active and passive mixers, the role of frequency range, output voltage swing, drive capability, phase noise, output waveform, supply sensitivity, and power dissipation in oscillator design. The lesson also delves into the Barkhausen criteria for achieving oscillation, the concept of negative resistance, and the design of a three-stage ring oscillator. It concludes with a discussion on cross-coupled oscillators and voltage control oscillators. For instance, it explains how a three-stage ring oscillator can provide the necessary 360° phase shift for oscillation.

Video Highlights

00:25 - Oscillator design and its performance parameters
04:25 - Explanation of oscillator and 2nd Barkhausen criterion
09:04 - Two pole feedback and three stage ring system
11:27 - Explanation of the three-stage ring oscillator design
15:40 - One port view of oscillators
24:40 - Tuned Oscillator
28:56 - Cross coupled oscillator

Key Takeaways

- Oscillators are crucial components in mixer design, with key performance parameters including frequency range, output voltage swing, drive capability, phase noise, output waveform, supply sensitivity, and power dissipation.
- The Barkhausen criteria, which stipulates a total phase shift of 360° and a loop gain greater than or equal to 1, is essential for achieving and sustaining oscillation.
- Negative resistance can be generated using active circuits, which can be used to cancel out the resistance in a circuit and sustain oscillation.
- A three-stage ring oscillator can provide the necessary 360° phase shift for oscillation, with each stage contributing a frequency-dependent phase shift of 60°.
- Cross-coupled oscillators and voltage control oscillators are other types of oscillators discussed, with the former requiring a gain (GM RP) greater than or equal to 1 for oscillation.