DPT for Linear and Nonlinear Distortion - Part II — Lesson 6

This lesson covers the fundamentals of software defined radios and their practical applications, with a focus on digital pre-distortion techniques for linear and non-linear distortion. It delves into the IQ imbalance in transmitters, the effects of phase shifts, and the impact of power amplifier non-linearity. The lesson also explores different approaches to remove distortion, including two-step processes and single-step processes. It provides a detailed explanation of how to use models to compensate for both IQ imbalance and power amplifier non-linearity. An illustrative example is provided through a demo showing how to tune coefficients to reduce IQ imbalance and out of band distortion.

Video Highlights

00:18 - Effect of IQ imbalance on the transmitter output
03:40 - Structure of the homodyne transmitter
05:22 - Effect of IQ imbalance on the phase and gain characteristic
10:50 - Removal for linear and nonlinear distortions
15:30 - Demonstration of two-step process to remove IQ imbalance and the nonlinearity
20:30 - Demonstration of IQ imbalance
26:43 - Single step process to remove both the IQ imbalance and the nonlinearity of power amplifier simultaneously
30:50 - Results - power spectrum density and constellation diagram

Key Takeaways

- Software defined radios use digital pre-distortion techniques to manage linear and non-linear distortion.
- IQ imbalance in transmitters can cause phase shifts and alter signal components.
- Power amplifier non-linearity can significantly distort signals.
- Distortion can be removed through two-step processes that first address IQ imbalance and then tackle power amplifier non-linearity.
- Single-step processes can also be used, employing models that compensate for both types of distortion simultaneously.
- The lesson demonstrates how to tune coefficients to reduce IQ imbalance and out of band distortion.