RF Receiver Nonlinearity Correction Using Digital Feedback
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Solution Overview
Problem
High-frequency communication networks face nonlinearities in signal processing due to limitations in electronic components, which are exacerbated by aging and temperature variations, necessitating a solution to correct these nonlinearities digitally without prior signal knowledge.
Innovation Solution
A circuit with a reception chain and correction chain that includes a low-noise amplifier, time-interleaved analog-to-digital converter, and application-specific integrated circuit (ASIC) for processing analog signals, using filters and gain correction to remove dynamic nonlinearities from digital signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-frequency carriers are used for high-rate communication networks, then data rate is improved, but dynamic nonlinearities occur in the signal processing chain
Solution Approach 1:
The patent measures the dynamic nonlinearities generated by the reception chain and uses this harmful information to create a correction signal. By cubing the digital signal and filtering it to reconstruct the nonlinearities, the system converts the harmful distortion into a beneficial correction that is subtracted from the original signal, thereby eliminating the nonlinearities while maintaining high-frequency operation
Solution Approach 2:
The patent implements a feedback mechanism where the output of the reception chain is fed back through a correction chain that generates a correction signal based on the measured nonlinearities. This correction signal is then subtracted from the original signal, creating a closed-loop system that continuously compensates for dynamic nonlinearities, allowing the system to maintain high data rates while correcting the harmful effects
2Reliability
If electronic components are used at high frequencies, then communication network performance is improved, but component aging and temperature variations exacerbate nonlinearities
Solution Approach 1:
The patent implements a self-correcting system where the reception chain automatically measures its own dynamic nonlinearities and generates correction signals without external intervention. The system uses its own output signal to create the correction, making it autonomous and adaptive to changing conditions such as component aging and temperature variations, thereby maintaining signal linearity independently of environmental factors
3Measurement precision
If digital processing is applied to correct nonlinearities, then signal quality is improved, but device complexity increases
Solution Approach 1:
The patent transforms the correction problem by changing the domain of operation. Instead of attempting complex real-time filtering in the time domain, the system cubes the digital signal and applies filtering in a transformed domain where the nonlinearity correction becomes a linear operation. This parameter change simplifies the device complexity while achieving high signal quality correction
Data Source
AI summary
A reception element receives an analog signal. The received analog signal is converted by a reception chain into a digital signal. Based on the digital signal and a first filtering operation, a correction chain generates a correction digital signal reconstituting dynamic nonlinearities generated by the reception chain. A corrected signal from which the reconstituted dynamic nonlinearities have been removed is then generated by subtracting the correction digital signal from the digital signal.