Fractional Spurs — Lesson 5

This lesson covers the concept of CMOS RF Integrated Circuits, focusing on frequency synthesis techniques. It delves into the development of a fractional synthesizer and the identification of spurious frequencies. The lesson also explores the concept of phase look loop and the need for programmable division. It further discusses the limitations of restricted loop bandwidth and the need for better phase noise performance. The lesson also explains the concept of fractional synthesis and how it can be used to improve the performance of the system. For instance, the lesson uses the example of a system that needs to divide by a fraction, not just an integer, to increase the loop bandwidth.

Video Highlights

00:24 - Introduction and recap of previous lesson
12:42 - Control voltage glitches and fundamental frequency
33:48 - Concept of pulse width modulated signal and sigma delta modulation
41:15 - Feedback control system in sigma delta modulation and its advantages
56:20 - Conclusion of the lecture with a note on the next topic of discussion

Key Takeaways

- Frequency synthesis techniques are crucial in the development of CMOS RF Integrated Circuits.
- The fractional synthesizer allows for larger loop bandwidth and better phase noise performance.
- The concept of phase lock loop and programmable division is essential in frequency synthesis.
- The limitations of restricted loop bandwidth necessitate the need for better phase noise performance.
- The comparison between integer n and fractional n techniques provides insights into their respective advantages and disadvantages.
- Sigma delta modulation offers a potential solution to the limitations of the fractional n technique.