Motivation First Cut Design - Part I — Lesson 1

This lesson covers the concept of CMOS RF integrated circuits, focusing on low noise amplifiers. It begins with a numerical problem to understand the combined gain and noise figure of a system with two blocks, each having different gains and noise figures. The lesson then delves into the definition of noise figure and how it relates to the noise contributed by the amplifier and the source. It further explains the importance of designing a low noise amplifier and its placement in a system. The lesson also discusses the Friis equation, which relates the noise figure of a system to the gain of the first stage. It concludes with the desirable characteristics of a low noise amplifier and the strategies to design one.

Video Highlights

02:16 - How noise is generated in an amplifier and how it affects the signal
12:22 - Importance of gain in the first stage of an amplifier (Low noise amplifier)
23:59 - Characteristics of low noise amplifier
33:01 - Matching network
44:44 - Discussion on the importance of having a resistive component in the load for effective matching

Key Takeaways

- The combined gain of a system is the sum of the gains of its individual blocks.
- The noise figure of a system does not simply add up; it depends on the gain of the first stage.
- A low noise amplifier is crucial in a system as it ensures that the noise contributed by the amplifier is minimal compared to the noise from the source.
- The gain of the first stage is critical as it determines the overall noise factor of the system.
- The input and output impedance of a low noise amplifier should be matched to the impedance of the source and the next stage respectively for maximum power transfer and to conserve the signal shape.
- The noise figure of a low noise amplifier should be as low as possible for it to be competitive.