Full Duplex Amplifier Layout for Mid-Band Bleed-Over Isolation
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Solution Overview
Problem
Conventional amplifiers in full duplex communication systems face instability and bleed-over issues due to the need to amplify both upstream and downstream signals within a shared spectral band, leading to undesirable interference and amplification of unwanted spectral portions.
Innovation Solution
The implementation of a bidirectional amplification subsystem with separate downstream and upstream amplifiers, along with a mid-band amplifier that can selectively transmit signals in either direction, using diplexers and switched bandpass filters to isolate and filter out bleed-over signals before amplification, ensuring stable amplification across the full duplex spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single amplifier is used to amplify both upstream and downstream signals in a shared spectral band, then device complexity is reduced, but amplifier instability and bleed-over interference occur
Solution Approach 1:
The patent divides the single amplifier into separate upstream and downstream amplifiers, with each amplifier dedicated to a specific signal direction. This segmentation eliminates the bleed-over interference that occurs when a single amplifier handles both directions, as each amplifier operates independently on its designated signal path.
Solution Approach 2:
The patent extracts and removes the problematic shared amplification function from the single amplifier configuration. By taking out the upstream and downstream amplification functions and assigning them to separate amplifiers, the harmful bleed-over effect is eliminated while maintaining the necessary signal amplification.
2Reliability
If separate upstream and downstream amplifiers are used, then signal stability is improved, but device complexity increases
Solution Approach 1:
The patent introduces a bidirectional amplifier that can function as either an upstream or downstream amplifier depending on the operational mode. This multi-functional component reduces the overall system complexity by replacing what would otherwise require multiple dedicated amplifiers, while still maintaining the signal stability benefits of separate amplification paths.
Solution Approach 2:
The patent implements dynamic switching between upstream and downstream amplification modes using a bidirectional amplifier. The system can adaptively change the amplifier's function based on real-time operational requirements, optimizing performance while reducing the number of fixed components needed in the system.
3Productivity
If bidirectional amplification is implemented without filtering, then full duplex transmission is enabled, but bleed-over interference degrades signal quality
Solution Approach 1:
The patent introduces diplexers and bandpass filters as intermediary components between the bidirectional amplifier and the transmission lines. These intermediaries selectively pass desired frequency bands while blocking unwanted signals, thereby eliminating bleed-over interference without compromising the full duplex transmission capability.
Solution Approach 2:
The patent applies frequency-selective filtering at specific locations in the signal path using diplexers and bandpass filters. Each filter is designed with local quality characteristics tailored to its specific frequency band requirements, allowing precise control over which signals are amplified and which are blocked to prevent interference.
Data Source
AI summary
An amplification subsystem for a communication system includes a downstream amplifier configured to transmit a downstream signal within a first frequency range, an upstream amplifier configured to transmit an upstream signal within a second frequency range, and a bidirectional amplifier configured to selectively transmit a mid-band signal in either of the upstream and downstream direction.