DPD Feedback Band-Pass Filtering for Wideband Linearization
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Solution Overview
Problem
Current digital predistortion (DPD) systems face limitations in increasing bandwidth without significantly increasing complexity and cost, particularly in multi-channel wideband wireless transmitters, leading to inefficiencies and higher power consumption due to stringent RF/IF filter requirements and complex algorithm design.
Innovation Solution
The implementation of a DPD feedback signal with a narrow band-pass filter and a direct learning algorithm, which reduces the need for digital FIR filters and multi-pole ceramic filters, allowing for a shared filter in multiband applications and lower sampling rates, thereby extending bandwidth without costly modifications to existing digital platforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the DPD processing speed is increased to meet higher instantaneous bandwidth requirements, then the bandwidth capability is improved, but the system cost and power consumption increase due to higher sampling rates in FPGAs, DACs, and ADCs
Solution Approach 1:
The patent segments the wideband signal processing into multiple narrowband parallel channels. Each channel is processed independently at a lower sampling rate, avoiding the need for high-speed processing of the entire wideband signal. This segmentation allows the system to achieve wideband coverage through frequency division while maintaining lower processing speeds in each segment, thereby reducing FPGA, DAC, and ADC cost and power consumption.
2Speed
If the DPD processing speed is increased to meet higher instantaneous bandwidth requirements, then the bandwidth capability is improved, but the power consumption increases due to higher sampling rates
Solution Approach 1:
The patent segments the wideband signal processing into multiple narrowband parallel channels. Each channel is processed independently at a lower sampling rate, avoiding the need for high-speed processing of the entire wideband signal. This segmentation allows the system to achieve wideband coverage through frequency division while maintaining lower processing speeds in each segment, thereby reducing FPGA, DAC, and ADC cost and power consumption.
3Speed
If wider instantaneous bandwidth is implemented in DPD, then the bandwidth capability is improved, but the memory effects increase causing more complex algorithms
Solution Approach 1:
The patent segments the wideband signal processing into multiple narrowband parallel channels. By processing each narrowband channel independently, the memory effects are confined to each segment rather than affecting the entire wideband signal. This reduces the complexity of the DPD algorithm in each segment, as the memory depth required is proportional to the segment bandwidth rather than the total bandwidth.
Solution Approach 2:
The patent transforms the time-domain wideband processing problem into a frequency-domain parallel processing structure. By using frequency division to separate the wideband signal into multiple narrowband channels, the system addresses memory effects in the frequency dimension rather than dealing with them in the time domain, thereby reducing algorithmic complexity.
4Speed
If higher processing speed is achieved, then the bandwidth capability is improved, but new digital platform design efforts are required taking several months and significant resources
Solution Approach 1:
The patent segments the wideband signal processing into multiple narrowband parallel channels. Each channel can be processed using existing, proven digital platform components designed for narrowband operation. This avoids the need to design and validate an entirely new high-speed digital platform, significantly reducing development time and resource requirements.
Data Source
AI summary
A digital predistortion linearization method is provided for increasing the instantaneous or operational bandwidth for RF power amplifiers employed in wideband communication systems. Embodiments of the present invention provide a method of increasing DPD linearization bandwidth using a feedback filter integrated into existing digital platforms for multi-channel wideband wireless transmitters. An embodiment of the present invention utilizes a DPD feedback signal in conjunction with a low power band-pass filter in the DPD feedback path.