Wideband DPD Feedback Filtering for Multi-Channel Bandwidth Expansion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current digital predistortion (DPD) systems face challenges in increasing bandwidth without significantly increasing complexity and cost, particularly in multi-channel wideband wireless transmitters, leading to inefficiencies and higher power consumption.
Innovation Solution
The implementation of a DPD feedback signal with a narrow band-pass filter in the feedback path, allowing for extended bandwidth without modifying digital signal processing components, and the use of direct learning algorithms and analog filters to reduce the need for complex digital FIR filters and high-cost ceramic filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If DPD processing speed is increased to meet higher instantaneous bandwidth requirements, then bandwidth capability is improved, but power consumption and system cost increase due to higher sampling rates in DPD, DACs, and ADCs
Solution Approach 1:
The patent segments the DPD processing function by introducing a feedback path with a narrow band-pass filter that separates the wideband DPD signal into narrower frequency components. This allows the DPD algorithm to process multiple narrower bands sequentially or in parallel at lower sampling rates, thereby reducing power consumption while maintaining overall wideband performance through constructive combination of the segmented signals.
2Speed
If DPD processing speed is increased to meet higher instantaneous bandwidth requirements, then bandwidth capability is improved, but system cost increases due to higher sampling rates in DPD, DACs, and ADCs
Solution Approach 1:
The patent segments the wideband signal processing into multiple narrower band processing paths, each operating at lower sampling rates. This segmentation reduces the complexity of individual processing components (DPD, DAC, ADC) while maintaining overall wideband capability through the feedback mechanism that combines the segmented signals.
Solution Approach 2:
The patent introduces a feedback path with a narrow band-pass filter as an intermediary element. This feedback mechanism acts as a mediator that processes wideband signals through multiple narrower intermediate stages, reducing the complexity requirements of individual components while achieving overall wideband performance.
3Speed
If instantaneous bandwidth is increased beyond 25 MHz, then bandwidth capability is improved, but memory effects increase causing DPD algorithm complexity and design time to increase
Solution Approach 1:
The patent segments the wideband signal into multiple narrower frequency bands using the feedback path with band-pass filters. Each segmented band experiences reduced memory effects, allowing the DPD algorithm to operate with lower complexity for each segment while achieving overall wideband linearization through combination of the segmented processing results.
Data Source
AI summary
A method of operating a communications system includes receiving a signal at a digital predistorter (DPD), introducing predistortion to the signal using the DPD, and converting the predistorted signal to an analog signal using a digital-to-analog converter having a first bandwidth. The method also includes amplifying the analog signal, sampling the amplified signal using an analog-to-digital converter having a second bandwidth less than the first bandwidth, and extracting coefficients of the DPD from the sampled signal.