Signal Predistortion Circuit Dual-Loop Architecture
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Solution Overview
Problem
Conventional digital predistortion (DPD) circuits face challenges in determining accurate predistortion parameters due to severe signal coupling between transmission-end (TX) and reception-end (RX) paths, which is exacerbated by the close proximity of these paths, leading to inefficiencies and increased costs when attempting to insulate them effectively.
Innovation Solution
The proposed signal predistortion circuit configuration employs a dual-loop architecture with separate transmitting and receiving circuits and analog-front-end (AFE) circuits, where the minimum distance between certain circuits is optimized to reduce signal coupling, allowing for improved insulation and parameter determination without the need for additional circuit elements or high-end noise reduction algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the distance between TX path and RX path is reduced to optimize circuit area, then circuit area is reduced, but signal coupling between TX path and RX path increases
Solution Approach 1:
The system is divided into two independent training loops: first training loop uses first TX path and first RX path, second training loop uses second TX path and second RX path. This segmentation allows each loop to be trained independently with optimized spacing, reducing signal coupling in each individual loop while maintaining compact overall circuit area.
Solution Approach 2:
The patent introduces a cross-path coupling compensation mechanism where the second RX path receives signals from both first TX path and second TX path, and first RX path receives signals from both first TX path and second TX path. This dimensional expansion in signal routing allows for sophisticated interference cancellation algorithms that can separate and compensate for coupled signals.
2Object-affected harmful factors
If additional reception path is added to prevent signal coupling, then signal coupling is reduced, but circuit complexity and cost increase
Solution Approach 1:
Each RX path is designed to perform multiple functions: primary reception function for its designated TX path, and secondary interference reception function for the other TX path. This multi-functionality allows the system to use existing circuit elements for multiple purposes, reducing the need for additional dedicated components while maintaining insulation performance.
Solution Approach 2:
The system implements feedback mechanisms where received signals from both RX paths are processed to extract information about signal coupling, and this information is used to adjust predistortion parameters dynamically. This feedback loop enables real-time compensation for signal coupling without requiring additional physical insulation structures.
3Object-affected harmful factors
If additional reception path is added to prevent signal coupling, then signal coupling is reduced, but circuit area increases
Solution Approach 1:
The patent merges the functions of multiple RX paths by having them share common signal processing resources and by designing the spacing and routing such that second RX path serves both second TX path and first TX path. This merging approach consolidates circuit elements and reduces total area compared to having completely separate dedicated paths for each function.
4Object-affected harmful factors
If signal coupling is reduced by increasing distance, then signal coupling is reduced, but circuit area increases
Solution Approach 1:
The patent applies different spacing strategies to different parts of the circuit: first TX path and first RX path are positioned with optimized spacing for their primary function, while second TX path and second RX path are positioned with different optimized spacing. This local optimization allows each pair to have minimal area while maintaining acceptable coupling levels, and the cross-path compensation handles the remaining interference.
Data Source
AI summary
A signal predistortion circuit configuration includes a digital predistortion circuit, a first transceiver, a first analog front-end (AFE) circuit, a second transceiver, and a second AFE circuit. The digital predistortion circuit outputs a first transmission signal according to first predistortion parameters and outputs a second transmission signal according to second predistortion parameters, and the digital predistortion circuit determines whether to adjust the first predistortion parameters according to a first reception signal and determines whether to adjust the second predistortion parameters according to a second reception signal. A transmitting circuit of the first transceiver, the first AFE circuit, and a receiving circuit of the second transceiver jointly generates the first reception signal according to the first transmission signal. A transmitting circuit of the second transceiver, the second AFE circuit, and a receiving circuit of the first transceiver jointly generates the second reception signal according to the second transmission signal.