Multi-Band RF Predistortion With Lower Sampling Complexity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional digital predistortion techniques are not optimal for multi-band transmitters, as they face challenges in managing non-linear signal distortion and require high sampling rates and complex digital upconversion processes, making them inefficient and costly.
Innovation Solution
The implementation of Radio Frequency Digital Predistortion (RF-DPD) in a multi-band transmitter, which digitally predistorts RF signals after upconversion, reducing sampling rates and eliminating the need for additional upconversion paths to handle inter-band distortion products, and allows for separate synthesis of intra-band and inter-band distortion products for each band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional baseband digital predistortion is used in multi-band transmitters, then non-linear distortion can be compensated, but the sampling rate requirements and computational complexity increase significantly
Solution Approach 1:
The patent segments the multi-band signal into separate band-specific predistortion processes. Each band is handled independently with its own predistortion function, avoiding the need to process all bands simultaneously at full sampling rate. This segmentation reduces the overall computational complexity while maintaining distortion compensation effectiveness for each band.
Solution Approach 2:
The patent changes the sampling rate parameter dynamically - using full sampling rate for single-band signals but reducing to band-specific lower sampling rates for multi-band signals. This parameter adaptation allows the system to maintain adequate predistortion performance while significantly reducing computational burden for multi-band operations.
2Reliability
If conventional baseband digital predistortion is used in multi-band transmitters, then non-linear distortion can be compensated, but additional upconversion paths are required to handle inter-band distortion products
Solution Approach 1:
The patent applies predistortion to each band before the upconversion process. By pre-compensating the non-linear distortion in the baseband for each band individually, the system eliminates the need for additional upconversion paths that would otherwise be required to handle inter-band distortion products generated after upconversion.
Solution Approach 2:
The patent extracts and handles inter-band distortion products separately through band-specific predistortion functions. Instead of allowing these distortion products to be generated and then requiring additional processing paths, the system extracts and compensates for them in advance during the baseband predistortion stage for each band.
3Use of energy by moving object
If wideband power amplifiers are operated close to saturation to maximize power efficiency, then power efficiency is improved, but significant non-linear signal distortion is introduced to wideband signals
Solution Approach 1:
The patent applies preliminary anti-action by implementing digital predistortion that pre-compensates for the non-linear distortion that will be introduced by the power amplifier. The predistortion function applies an inverse characteristic to the input signal, creating a pre-distorted signal that, when passed through the non-linear PA, results in linearized output. This allows the PA to operate close to saturation for maximum efficiency while the predistortion counteracts the harmful non-linear effects.
Data Source
Figure 1
Figure 2A~2C
Figure 3
AI summary
Systems and methods for radio frequency digital predistortion in a multiband transmitter (72) are disclosed. In one embodiment, the multi-band transmitter includes a digital upconversion system (76) configured to digitally upconvert digital input signals to provide digital radio frequency signals. Each digital input signal and thus each digital radio frequency signal corresponds to a different band of a multi-band transmit signal to be transmitted by the multi-band transmitter (72). The multi-band transmitter (72) also includes a radio frequency digital predistortion system configured to digitally predistort the digital radio frequency signals to provide predistorted digital radio frequency signals, and a combiner (80) configured to combine the predistorted digital radio frequency signals to provide a multi-band predistorted digital radio frequency signal.