Multiband Digital Predistortion Using Condensed Frequency Shifting
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Solution Overview
Problem
Power amplifiers used in radio frequency communications exhibit nonlinear characteristics, leading to distortion issues, especially when operating near maximum output power, and existing digital predistortion methods require high sampling rates for multiband signals, which can be resource-intensive and inefficient.
Innovation Solution
The method involves frequency shifting multiband signals into a condensed frequency window, reducing the sampling bandwidth and applying digital predistortion to the shifted signals, allowing for efficient processing and amplification with reduced sampling rates, and periodically adjusting predistortion parameters to minimize nonlinear distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If digital predistortion is applied to multiband signals occupying a large frequency span, then nonlinear distortion compensation is achieved, but the sampling rate must be very high which increases resource consumption and processing complexity
Solution Approach 1:
The patent transforms the frequency domain parameters of multiband signals by applying frequency shifting to condense them into a narrower window. This parameter transformation allows the same signal processing to be performed at a lower sampling rate, directly resolving the contradiction between maintaining distortion compensation quality and reducing sampling rate requirements
Solution Approach 2:
The patent introduces frequency shifting as an intermediary processing step between signal reception and digital predistortion. This intermediary transformation creates a condensed frequency representation that enables efficient processing while preserving the essential characteristics needed for nonlinear distortion compensation
2Measurement precision
If high sampling rates are used to process multiband signals with large frequency spans, then signal processing accuracy is maintained, but resource consumption and system complexity increase
Solution Approach 1:
By changing the frequency parameter through condensation, the system achieves accurate signal processing at lower sampling rates. The frequency shifting operation preserves signal integrity while reducing the numerical value of the sampling rate parameter, thereby maintaining precision without requiring complex high-speed processing hardware
3Reliability
If dedicated circuitry is implemented for each RF band, then band-specific processing performance is optimized, but device complexity and cost increase
Solution Approach 1:
The patent creates a universal processing architecture where frequency shifting condenses multiple RF bands into a common frequency window. This allows a single digital predistortion processor to handle multiple bands simultaneously, eliminating the need for dedicated circuitry for each band while maintaining band-specific processing performance through the preserved frequency relationships
Data Source
AI summary
Disclosed are methods, systems, devices, apparatus, media, design structures, and other implementations, including a method for digital predistortion of multiband signals that includes receiving a plurality of input signals respectively associated with multiple radio frequency (RF) bands, with the plurality of input signals occupying an input frequency span corresponding to a difference between a maximum frequency in a highest of the multiple RF bands and a minimum frequency in a lowest of the multiple RF bands. The method further includes frequency shifting at least one signal from the plurality of input signals to produce condensed shifted signals, each corresponding to a respective one of the plurality of input signals, occupying a condensed frequency span smaller than the input frequency span, and processing the condensed shifted signals, including applying digital predistortion to the condensed shifted signals.