Nonlinearity Specifications — Lesson 4

This lesson covers the distortion parameters and the impact of such distortion on signal quality. The lesson explains the concept of Intermodulation Distortion and its relation with input power. It also discusses the conversion of power from watt to dB and the importance of impedance matching in RF circuits. The lesson further elaborates on the calculation of signal power and voltage, and the impact of increasing input signal power on second and third order distortions. It introduces the concepts of Intercept Point, 1 dB gain compression point, Carrier to Intermodulation ratio, and Spurious Free Dynamic Range (SFDR). The lesson concludes with a discussion on multi-carrier or wideband signals and the concept of Peak to Average Power Ratio.

Video Highlights

00:18 - Signal power for two tone and IMD component
14:55 - Non linear specification and gain compression point
20:56 - Carrier to intermodulation ration
24:33 - Spurious Free Dynamic Range (SFDR) and its calculation
27:22 - Peak to average power ratio

Key Takeaways

- Distortion due to power amplifier nonlinearity can significantly impact signal quality in Software Defined Radios.
- Intermodulation Distortion (IMD) is more important when it comes near to the actual signal.
- The Intercept Point (IPn) and 1 dB gain compression point are crucial parameters in communication systems.
- The Carrier to Intermodulation ratio (C/I ratio) and Spurious Free Dynamic Range (SFDR) can be calculated using known signal power and IMD power.
- In multi-carrier or wideband signals, the Peak to Average Power Ratio (PAPR) is a critical factor as it determines the efficiency of the power amplifier.