RF Power Amplifier Predistortion With Single-Path Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing RF power amplifiers face challenges in achieving optimal power efficiency while minimizing spectral leakage and distortion, particularly when operating near saturation, due to nonlinearity, which complicates the use of predistortion techniques and increases power consumption and complexity.
Innovation Solution
A transmitter system with a digital predistortion (DPD) device that performs amplitude-to-amplitude and amplitude-to-phase modulation compensation using a feedback path with a processor to determine and apply phase and amplitude error compensation signals, allowing the power amplifier to operate closer to its saturation region while reducing distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the power amplifier operates close to its saturation region to improve power efficiency, then power consumption efficiency is improved, but spectral leakage and in-band distortion increase due to nonlinearity
Solution Approach 1:
The system applies predistortion to the input signal before amplification, pre-compensating for the nonlinear effects of the power amplifier. This preliminary action counteracts the distortion that would otherwise occur during saturation operation, enabling high power efficiency without excessive spectral leakage or in-band distortion
Solution Approach 2:
The system employs a feedback path that monitors the output signal and compares it with the input signal to generate error signals. These error signals are used to continuously adapt and update the predistortion parameters, ensuring that the predistortion accurately compensates for amplifier nonlinearities under varying operating conditions
2Manufacturing precision
If a closed loop predistortion approach is used to adapt to amplifier nonlinearities in real time, then distortion compensation is improved, but device complexity and power consumption increase
Solution Approach 1:
The system extracts only the essential error information (amplitude and phase differences) from the feedback path and uses this simplified data to drive the predistortion. By taking out only the necessary correction signals rather than processing the entire signal spectrum, the system achieves effective distortion compensation with reduced complexity
Solution Approach 2:
The system changes the parameters of the input signal (amplitude and phase) based on error measurements from the feedback path. By dynamically adjusting these parameters through predistortion, the system compensates for amplifier nonlinearities without requiring complex real-time modeling or processing
Data Source
AI summary
Exemplary embodiments of the invention include a transmitter system configured to predistort an input signal to generate a target output signal. An exemplary transmitter system includes a forward path including a predistortion device coupled with an amplifier, the forward path configured for predistorting an input signal to the predistortion device in response to a phase error compensation signal and an amplitude error compensation signal in order to generate a desired output signal for the output signal of the amplifier, and a feedback path including a processor configured for generating the phase error compensation signal and the amplitude error compensation signal based on a comparison of the input signal with phase and amplitude information of the output signal of the amplifier, wherein the phase and amplitude information of the amplifier are transmitted to the processor on a single path of the feedback path. Other methods and apparatuses are also presented herein.