Absorptive Filter for 5G Signal Reflection Reduction
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Solution Overview
Problem
Current wireless interface devices designed for Wi-Fi and 4G cellular standards are inadequate for next-generation 5G and faster Wi-Fi standards, as they struggle to handle higher frequencies and more stringent latency demands, leading to signal reflection issues that impair the accuracy of feedback loops and performance metrics like error vector magnitude (EVM) and power amplifier linearity.
Innovation Solution
The implementation of absorptive filters that split signals into two paths with phase-shifting, causing destructive interference of reflected signals at the input port, thereby reducing signal reflections and improving the accuracy of feedback loops and performance metrics by combining the filtered signals with aligned phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional filters are used at higher frequencies, then signal filtering is provided, but signal reflections increase by 10-15 decibels
Solution Approach 1:
The filter is divided into multiple filter units (first filter unit, second filter unit, third filter unit) arranged in different branches. Each filter unit processes a portion of the signal independently, and their combined effect reduces overall signal reflections while maintaining filtering performance at higher frequencies.
Solution Approach 2:
The filter employs an asymmetric structure with different branch configurations (first branch with first and second filter units, second branch with third filter unit). This asymmetric arrangement creates destructive interference patterns for reflected signals, reducing reflections by 10-15 decibels while preserving the desired signal.
2Measurement precision
If filters are added to reduce reflections, then feedback loop accuracy improves, but device complexity increases
Solution Approach 1:
Multiple filter units are merged into a single integrated filter structure with shared components and common input/output ports. The first, second, and third filter units are combined in a way that achieves reflection reduction through their collective arrangement, balancing improved feedback accuracy with controlled device complexity.
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
The absorptive filters significantly reduce signal reflections by 10-15 decibels, enhancing the accuracy of feedback loops and improving EVM and power amplifier linearity, allowing for more precise control and efficient operation of wireless interface devices at higher frequencies.
Implementation Method 1
The reflected split signal from the phase-shifted filtering path is phase-shifted again during propagation back toward the input port. For example, one split signal can be shifted by ninety degrees (90°) twice, resulting in a 180° phase shift. The double phase shifting of one reflected split signal causes the two reflected split signals to destructively interfere at the input port of the filter.
Data Source
AI summary
An apparatus is disclosed with an absorptive filter. In an example aspect, an apparatus has a filter including a first filter port and a second filter port. The filter also includes a hybrid coupler, a signal combiner, a first filter unit, and a second filter unit. The hybrid coupler includes a first hybrid port, a second hybrid port, and a third hybrid port, with the first hybrid port coupled to the first filter port. The signal combiner is coupled to the second filter port. The first filter unit is coupled between the second hybrid port and the signal combiner. The second filter unit is coupled between the third hybrid port and the signal combiner.