Parallel Feed Circuit Phase Layout for PIM Cancellation
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Solution Overview
Problem
Current base station feed circuits with semiconductor-based digital phase shifters have low third-order intercept points (IP3), leading to high passive intermodulation (PIM) interference, which affects uplink throughput and requires costly receiving/transmitting separation architectures, complicating layout and increasing costs.
Innovation Solution
A feed circuit design with phase shift elements on multiple parallel branches, where phase shift elements between semiconductor modules generate a fixed phase difference to cancel PIM signals, improving the PIM indicator without the need for receiving/transmitting separation architectures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If semiconductor-based digital phase shifters are used in the feed circuit, then the phase shifting function is achieved, but the third-order intercept point (IP3) is low, leading to high passive intermodulation (PIM) interference
Solution Approach 1:
The feed circuit is divided into N parallel branches, each containing a semiconductor module. By segmenting the single-phase-shifter architecture into multiple parallel paths with phase shift elements, the PIM signals from each branch can be made to cancel each other through constructive and destructive interference, thereby reducing overall PIM interference while maintaining the phase shifting function
Solution Approach 2:
The invention converts the harmful PIM signals generated by semiconductor components into a beneficial cancellation effect. By carefully designing the phase relationships between multiple branches, the PIM signals from different branches interfere destructively at the output, transforming the harmful nonlinear distortion into a mechanism that reduces overall PIM interference
2Object-generated harmful factors
If receiving/transmitting separation architecture is used to reduce PIM impact, then the PIM interference is reduced, but the layout complexity and costs increase
Solution Approach 1:
The invention merges the phase shifting function and PIM reduction function into a single integrated feed circuit architecture. Instead of using separate receiving/transmitting paths with additional filters, the parallel branch structure with phase shift elements simultaneously achieves both phase control and PIM cancellation, simplifying the overall system architecture and reducing layout complexity
3Adaptability or versatility
If semiconductor components are used in the feed circuit, then the phase shifting capability is provided, but the PIM indicator is low, affecting uplink throughput rate
Solution Approach 1:
By segmenting the feed circuit into multiple parallel branches with phase shift elements, the system maintains full phase shifting capability while enabling PIM cancellation. This segmentation allows the circuit to achieve both adaptability (phase control) and improved productivity (higher uplink throughput) by reducing the PIM interference that would otherwise limit performance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively cancels PIM signals, enhancing the PIM indicator and reducing layout and cost complexities in base station devices, while maintaining power capacity and avoiding software compensation for PIM.
Implementation Method 1
the N−1 first phase shift elements are configured to generate a fixed phase difference between the N branches
Implementation Method 2
PIM caused by semiconductor components in semiconductor modules in the branches can be cancelled each other
Data Source
AI summary
Disclosed embodiments provide a feed circuit, an antenna device, a communication device, and a communication system that are configured to improve passive intermodulation (PIM). In the feed circuit, phase shift elements are disposed along a plurality of parallel branches to cancel PIM caused by semiconductor components in semiconductor modules in the branches.