Bandwidth Estimation Constants - Part II — Lesson 2

This lesson covers the method of open circuit time constants in CMOS RF integrated circuit design. It explains how to estimate bandwidth and improve design using this method. The lesson starts with a discussion on small signal parameters and their role in the design. It then moves on to the concept of open circuit time constant and how it can be used for back of the envelope hand calculations. The lesson also explains the impact of different components like load capacitance, resistance, and miller effect on the bandwidth. Towards the end, it provides a step-by-step guide on how to identify the culprits affecting the bandwidth and how to improve upon the design.

Video Highlights

00:24 - Introduction and small signal parameters
07:56 - Cascode or common gate structure to fix the miller effect problem
15:01 - Identification of the gate to source of device
42:24 - Buffer stage to reduce the resistance seen by it
54:11 - Analysis of the bandwidth of the design after all modifications

Key Takeaways

- The method of open circuit time constants is a useful tool in CMOS RF integrated circuit design.
- Small signal parameters play a crucial role in the design.
- Identifying the 'culprit' that is limiting the bandwidth and working on it can improve the design.
- Adding a buffer in front of a device can reduce the resistance it sees, thereby improving the bandwidth.
- The width and length of the mosfet can also be varied to improve the bandwidth.