Multi-Mode DPD Capture Circuit for GaN PA Linearity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Obtaining an accurate power amplifier (PA) model for digital predistortion (DPD) is challenging due to nonlinear behavior caused by charge trapping effects in GaN transistors, which affects the linearity and efficiency of RF systems, particularly in 4G and 5G wireless communications.
Innovation Solution
A multi-mode DPD capture circuit is introduced to capture feedback signals from PAs, offering configurable modes for timing and signal condition selection, allowing for reliable and specific data acquisition to improve the estimation of DPD coefficients and enhance the accuracy of predistortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If digital predistortion is applied to enhance PA linearity, then modulation accuracy and out-of-band emissions are improved, but the complexity of obtaining accurate PA models increases due to charge trapping effects
Solution Approach 1:
The patent implements dynamic capture timing that adapts to varying signal conditions and charge trapping effects. The capture circuit dynamically selects optimal timing windows based on real-time signal characteristics, allowing the DPD system to track time-varying PA behavior caused by charge trapping, thereby maintaining measurement precision without requiring overly complex static models
Solution Approach 2:
The system changes capture parameters (timing, signal conditions, measurement windows) based on operating conditions to optimize PA model accuracy. By adjusting these parameters dynamically, the system adapts to charge trapping effects without fundamentally changing the DPD architecture, resolving the contradiction between measurement precision and device complexity
2Reliability
If multiple capture modes are implemented to adapt to various signal conditions, then DPD coefficient estimation accuracy is improved, but the device complexity increases
Solution Approach 1:
The capture circuit is designed with multi-functionality, capable of operating in multiple capture modes (different timing windows, signal conditions, and measurement configurations). This universal design allows a single circuit to handle diverse signal conditions and charge trapping scenarios, improving DPD coefficient estimation accuracy without requiring separate dedicated circuits for each mode, thus limiting the increase in device complexity
3Measurement precision
If capture timing is optimized for specific signal conditions, then measurement precision is improved, but adaptability to varying signal conditions deteriorates
Solution Approach 1:
The capture timing is made dynamic rather than fixed, allowing the system to adapt to varying signal conditions. The capture circuit automatically adjusts timing windows and selection criteria based on real-time signal characteristics, maintaining measurement precision across different operating conditions while preserving adaptability to new signal types and conditions
Data Source
AI summary
Systems, devices, and methods related to performing digital predistortion in radio frequency (RF) systems are provided. A digital predistortion (DPD) arrangement includes a DPD actuator circuit to predistort, using DPD coefficients, at least a portion of an input signal, the DPD coefficients associated with a characteristic of a nonlinear component. The DPD arrangement further includes a DPD capture circuit to perform, based on a capture cycle timing, multiple captures of a feedback signal, the feedback signal indicative of an output of the nonlinear component; compute, based on one or more characteristics of the multiple captures, one or more criteria for a subsequent capture of the feedback signal; and perform, based on the one or more criteria, the subsequent capture of the feedback signal. The DPD arrangement circuit further includes a DPD adaptation circuit to update the DPD coefficients based at least in part on the subsequent capture.