RF Predistortion Feedback for MIMO Crosstalk Suppression
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Solution Overview
Problem
In MIMO wireless communication systems, the dense disposition of RF components on a small chip area leads to crosstalk nonlinear distortion, which increases the bandwidth of coupled signals, complicating circuit design and requiring higher hardware specifications for components like A-D and D-A converters.
Innovation Solution
A signal processing device is introduced that includes first and second circuits to generate pre-distortion signals for power amplifiers, using feedback paths to control the generation of these signals and reduce crosstalk nonlinear distortion by limiting signal bandwidth through band-pass filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If RF components are densely disposed on a small chip area, then chip area is reduced, but crosstalk nonlinear distortion increases
Solution Approach 1:
The patent applies preliminary anti-action by generating pre-distortion signals that anticipate and counteract the crosstalk nonlinear distortion before it occurs. The signal processing device processes input signals to generate corrected signals that pre-compensate for the expected distortion, thereby eliminating the harmful effect before it manifests in the output.
Solution Approach 2:
The patent implements feedback by using output signals from the power amplifiers as feedback inputs to the signal processing device. This feedback loop allows the system to continuously monitor the actual output and adjust the pre-distortion signals accordingly, maintaining accurate compensation despite variations in operating conditions.
2Quantity of substance
If crosstalk nonlinear distortion is present, then signal bandwidth increases, but circuit design complexity increases
Solution Approach 1:
The patent extracts only the necessary frequency components by using band-pass filters to remove out-of-band signals generated by crosstalk nonlinear distortion. Instead of handling the full expanded bandwidth, the system selectively extracts and processes only the relevant signal components, thereby reducing circuit design complexity.
3Speed
If high-speed A-D and D-A converters are used, then sampling frequency increases, but hardware cost increases
Solution Approach 1:
The patent removes out-of-band signals through band-pass filtering before they require high-speed processing. By eliminating unnecessary frequency components early in the signal chain, the system can use lower-speed, lower-cost A-D and D-A converters while still maintaining the required sampling frequency for the actual signal content.
Solution Approach 2:
The patent changes the signal parameters by applying pre-distortion and filtering to modify the signal characteristics. This transformation allows the use of lower sampling frequencies in the converters while maintaining signal integrity, thereby reducing hardware costs.
Data Source
AI summary
A signal processing device, used to suppress cross-talk nonlinear distortion of a RF front end circuit. The first circuit generates a first PD signal and a second PD signal according to a first input signal and a second input signal. The first PD signal and the second PD signal are provided to a first PA and a second PA of the RF front end circuit. The second circuit generates a first control signal and a second control signal according to a first output signal, a second output signal, a first DPD signal and a second DPD signal, so as to control the first circuit to generate the first PD signal and the second PD signal. The first PA generates the first output signal through a first filter having a first operating BW. The second PA generates the second output signal through a second filter having a second operating BW.