Analog I/Q Predistortion for Multi-Chain Signal Linearization
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Solution Overview
Problem
Classical adaptive linearization circuits for wireless communication devices with multiple transmission chains, such as Active Phased Array Antenna Systems, face challenges due to high area and power consumption, design complexity, and inefficiency, especially when each transmission chain requires local solutions.
Innovation Solution
A mixed-signal adaptive predistortion method is applied directly to I and Q analog baseband waveforms, using feedback signal demodulation, digital comparison, and analog predistortion, with analog to digital conversions performed below the Nyquist frequency to simplify architecture and reduce power consumption, while monitoring intermodulation out-of-band power and symbol error to prevent spectral regrowth and maintain symbol integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If classical adaptive linearization circuits are implemented locally for each transmission chain in multi-transmission chain devices, then linearization performance is improved, but area consumption, power consumption, and design complexity increase significantly
Solution Approach 1:
The patent combines multiple linearization circuits into a single shared circuit that serves multiple transmission chains. The linearization circuit processes signals from multiple chains through time-division or code-division multiplexing, eliminating the need for separate linearization circuits for each transmission chain while maintaining linearization performance.
Solution Approach 2:
The linearization circuit is designed to perform multiple functions by serving different transmission chains sequentially or concurrently through multiplexing techniques. A single circuit instance handles linearization for multiple chains, making the circuit universal rather than dedicated to a single chain.
2Reliability
If classical adaptive linearization circuits are implemented locally for each transmission chain, then linearization performance is improved, but area consumption increases
Solution Approach 1:
Multiple linearization circuits are merged into a single shared circuit that serves multiple transmission chains. The circuit uses time-division or code-division multiplexing to process signals from different chains, reducing the total area required from N separate circuits to one shared circuit.
Solution Approach 2:
The patent introduces time or code dimensions to resolve the spatial conflict. By processing multiple transmission chains in different time slots or using different codes, a single linearization circuit can serve multiple chains without requiring proportional area, effectively moving the differentiation from spatial to temporal/code domain.
3Reliability
If classical adaptive linearization circuits are implemented locally for each transmission chain, then linearization performance is improved, but power consumption increases
Solution Approach 1:
The patent merges multiple power-consuming linearization circuits into a single shared circuit. By consolidating the functionality, the total power consumption is reduced while maintaining linearization performance through multiplexed operation across multiple transmission chains.
Data Source
AI summary
A embodiment method, for linearizing a transmission signal resulting from a quadrature amplitude modulation of an analog baseband signal and a radiofrequency amplification, comprises a demodulation of a feedback signal taken from the transmission signal, a comparison between the demodulated feedback signal and the baseband signal, a digital calculation of a predistortion control signal based on the comparison, and an analog predistortion of the analog baseband signal controlled by the predistortion control signal.