Directional Coupler Amplifier Layout for Low-Noise Upstream Signals
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Solution Overview
Problem
Amplifier devices in broadband networks face challenges with noise in upstream signals due to the use of directional couplers with uniform signal loss characteristics, which affect signal quality and require costly upgrades when frequency ranges change.
Innovation Solution
The amplifier device employs two directional couplers with different signal loss characteristics to create separate upstream and downstream paths, using microstrip and ferrite directional couplers to optimize signal coupling and reduce noise, with one coupler optimized for downstream and the other for upstream frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If directional couplers with uniform signal loss characteristics are used, then device complexity is reduced, but upstream signal quality deteriorates due to increased noise
Solution Approach 1:
The patent applies local quality by assigning different signal loss characteristics to different directional couplers based on their specific function. The first directional coupler (downstream) has different loss characteristics than the second directional coupler (upstream), allowing each to be optimized for its specific signal path and frequency range, thereby improving upstream signal quality without excessive complexity
Solution Approach 2:
The patent segments the bidirectional amplifier into two separate signal paths with dedicated directional couplers. By dividing the system into downstream path (first directional coupler) and upstream path (second directional coupler), each component can be optimized independently for its specific function, resolving the contradiction between uniformity and performance
2Reliability
If diplex filters are used to separate upstream and downstream frequencies, then signal isolation is improved, but adaptability to frequency range changes deteriorates requiring costly upgrades
Solution Approach 1:
The patent applies universality by designing directional couplers that can handle both upstream and downstream frequencies without requiring frequency-specific diplex filters. The directional couplers provide frequency-agnostic signal separation through their coupling architecture, allowing the amplifier to adapt to different frequency ranges (e.g., DOCSIS 3.1, 3.1x, 4.0) without hardware upgrades
Solution Approach 2:
The patent extracts the frequency separation function from diplex filters and implements it through directional couplers. By removing the diplex filter component and using directional couplers with appropriate coupling factors, the system achieves signal isolation without the frequency-range limitation inherent in diplex filters
3Reliability
If a low-pass filter is added to the upstream amplifier path to increase isolation, then downstream signal protection is improved, but upstream noise increases
Solution Approach 1:
The patent applies parameter changes by optimizing the coupling factor and signal loss characteristics of the directional couplers to achieve the desired isolation without introducing noise. By carefully selecting the coupling parameters (e.g., 10dB, 20dB coupling factors) and loss characteristics, the system achieves sufficient isolation above the low-pass frequency while maintaining low noise in the upstream path
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 configuration improves upstream signal quality and reduces noise figure, maintaining downstream signal integrity without significant impairment, while eliminating the need for costly filter upgrades.
Implementation Method 1
a first directional coupler and a second directional coupler connected together so as to create separate upstream and downstream paths
Implementation Method 2
The first and second directional couplers may each comprise a microstrip directional coupler
Implementation Method 3
The first and second directional couplers may preferably each comprise a microstrip directional coupler connected to a ferrite directional coupler
Data Source
AI summary
There is provided an amplifier device comprising a first directional coupler (12: 30, 32) and a second directional coupler (14: 30′, 32′) connected together so as to create separate upstream (16) and downstream (18) paths in which amplifier means (24, 24′) are located, wherein the first and second directional couplers (12, 14: 30, 32; 30′, 32′) are configured to have different signal loss characteristics, one of the directional couplers having low signal loss characteristics for upstream signals and the other directional coupler having low signal loss characteristics for downstream signals. The signal loss characteristics are preferably the coupling loss of each directional coupler (12, 14: 30, 32; 30′, 32′). The first and second directional couplers may each comprise a microstrip directional coupler (30; 30′) connected to a ferrite directional coupler (50; 50′).