Wideband Multicarrier TDD Filter Unit With Segmented MXT and Circulator
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Solution Overview
Problem
Existing multiplexers are limited to narrow bandwidths, making them unsuitable for ultrawideband systems, and face challenges with high power levels, thermal effects, and Passive Intermodulation (PIM) stability, particularly in high-power applications like mobile base stations, where they become lossy and degrade radio performance.
Innovation Solution
A filter unit for wideband multicarrier TDD operation comprising a transmission multiplexer (MXT), at least one circulator, and a filter bank, where the MXT provides a first bandpass filtered signal to the circulator, which then passes it to the filter bank for further filtering, enabling low return loss and insertion loss across the ultrawideband frequency, allowing the use of standard or customized isolators and supporting high-power applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing multiplexers are used for narrow bandwidth applications, then they can maintain acceptable insertion loss and return loss, but they become unsuitable for ultrawideband systems and high-power applications
Solution Approach 1:
The multiplexer is divided into multiple independent bandpass filter channels, each handling a specific frequency band. This segmentation allows each filter to be optimized for its designated bandwidth while collectively covering an ultrawideband range, preventing the energy loss that occurs when a single narrowband filter attempts to handle wideband signals.
Solution Approach 2:
The multiplexer design provides multi-functionality by enabling simultaneous operation across multiple frequency bands (e.g., LTE bands 1, 3, 7, 8, 20) through a single device. The parallel filter structure allows the system to universally handle different bandwidth requirements and power levels without requiring separate multiplexers for each application.
2Power
If multiplexers are designed for high power levels (1W to 20W), then they can handle power amplifier outputs, but they require low losses to account for thermal effects and maintain PIM stability
Solution Approach 1:
By segmenting the power handling across multiple parallel filter channels rather than concentrating it through a single filter path, the thermal load is distributed. This reduces localized heating effects and maintains PIM stability even at high power levels of 1W to 20W from power amplifiers.
Solution Approach 2:
The independent bandpass filter structures act as intermediaries that selectively pass specific frequency bands while providing isolation between channels. This intermediary filtering reduces intermodulation products and maintains signal integrity under high-power conditions by preventing harmful frequency interactions.
3Adaptability or versatility
If multiplexers are designed for contiguous multicarrier signals, then they can handle satellite communication applications, but they are not optimized for noncontiguous multicarrier signals in mobile communication systems
Solution Approach 1:
The multiplexer uses segmented independent filter channels that can be selectively activated. This segmentation allows the same physical structure to handle both contiguous signals (by activating adjacent bands) and noncontiguous signals (by activating separated bands), providing signal type adaptability without requiring different hardware designs.
Solution Approach 2:
The system dynamically adapts to different signal types by selectively enabling or disabling specific filter channels based on the communication mode. For contiguous multicarrier signals, adjacent bands are activated; for noncontiguous signals, separated bands are activated. This dynamic configuration maintains ease of manufacture while achieving versatility.
4Ease of operation
If diplexers are realized with two bandpass filters connected using a T junction or common resonator, then they can implement TDD functionality, but they are limited to specific frequency bands and cannot simultaneously operate in multiple bands
Solution Approach 1:
Instead of using a single T junction or common resonator for all bands, the invention segments the filtering function into multiple independent bandpass filter channels. Each channel is optimized for a specific frequency band, allowing the system to simultaneously operate in multiple bands while maintaining proper TDD functionality in each band independently.
Solution Approach 2:
The invention merges multiple independent filter channels into a single multiplexer structure that handles all frequency bands. This combination allows simultaneous multiband operation while preserving the TDD functionality of each individual band, overcoming the limitation of traditional single-structure diplexers.
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 solution enables low return loss and insertion loss across the ultrawideband frequency, supports high-power applications, and allows for independent grouping of frequency-dependent elements, facilitating easy frequency band changes without requiring synchronized tuning of filters, thus addressing the limitations of existing multiplexers.
Implementation Method 1
The MXT comprises at least one first BP filter structure for first BP filtering of the TX wideband multicarrier signal. The filter bank comprises at least as many second BP filter structures as there are first BP filter structures for second BP filtering of the first BP filtered TX wideband multicarrier signal
Implementation Method 2
The at least one circulator is configured to receive the first BP filtered TX wideband multicarrier signal from the MXT and provide the first BP filtered TX wideband multicarrier signal to the filter bank
Data Source
AI summary
There is provided a filter unit for wideband multicarrier TDD operation. The filter unit comprises a transmission multiplexer (MXT), at least one circulator, and a filter bank. The MXT and the filter bank are connected via the at least one circulator. The MXT is configured to receive a transmission (TX) wideband multicarrier signal as 5 provided by at least one PA, and to provide a first bandpass (BP) filtered TX wideband multicarrier signal to the at least one circulator. The MXT comprises at least one first BP filter structure for first BP filtering of the TX wideband multicarrier signal. The at least one circulator is configured to receive the first BP filtered TX wideband multicarrier signal from the MXT and provide the first BP filtered TX 10 wideband multicarrier signal to the filter bank. The filter bank is configured to receive the first BP filtered TX wideband multicarrier signal from the at least one circulator, and to provide a second BP filtered TX wideband multicarrier signal towards an antenna port. The filter bank comprises at least as many second BP filter structures as there are first BP filter structures for second BP filtering of the first BP filtered TX 15 wideband multicarrier signal to provide the second BP filtered TX wideband multicarrier signal.