Carrier Aggregation Front-End with Split TDD Tx/Rx Filters
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Solution Overview
Problem
Legacy carrier aggregation architectures face challenges in optimizing TDD signal paths for simultaneous transmit and receive operations, leading to increased insertion loss, switching losses, and degradation of secondary component carrier signals due to non-ideal filter switching and amplitude/phase changes.
Innovation Solution
Implementing a carrier aggregation circuit with separate TDD Tx and Rx filters for each frequency band, ensuring identical initial stages in both filters, and using a common path for processing RF signals to reduce interference and optimize performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common filter is used for both transmit and receive operations in TDD carrier aggregation, then device complexity is reduced, but insertion loss increases and signal integrity deteriorates
Solution Approach 1:
The filter is segmented into two separate filters: a transmit filter for transmit operations and a receive filter for receive operations. This segmentation allows each filter to be optimized for its specific function, reducing insertion loss while maintaining manageable device complexity through modular architecture.
Solution Approach 2:
Each filter is designed with local quality optimization - the transmit filter is optimized for transmit signal characteristics while the receive filter is optimized for receive signal characteristics. This localized optimization reduces insertion loss for each specific operation mode.
2Adaptability or versatility
If transmit/receive switching is implemented in legacy architectures, then simultaneous transmit and receive operations are enabled, but switching losses increase and signal degradation occurs
Solution Approach 1:
The signal path is segmented into separate transmit and receive paths with dedicated filters for each path. This eliminates the need for transmit/receive switching while enabling simultaneous operations, thereby eliminating switching losses entirely.
Solution Approach 2:
A dual-filter architecture acts as an intermediary solution between the antenna and the transceiver, allowing simultaneous transmit and receive signals to pass through their respective filters without interference or switching requirements.
3Adaptability or versatility
If non-ideal filter switching is used in legacy carrier aggregation, then frequency band processing is achieved, but amplitude and phase changes degrade secondary component carrier signals
Solution Approach 1:
The filtering function is segmented into separate transmit and receive filters, each optimized for its specific operation mode. This eliminates the amplitude and phase variations caused by filter switching, maintaining consistent signal integrity for both primary and secondary component carriers.
Solution Approach 2:
Instead of using a single filter that switches between transmit and receive modes (which causes signal degradation), the invention inverts the approach by using two dedicated filters simultaneously, one for transmit and one for receive, thereby eliminating the switching-induced signal variations.
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 approach reduces insertion loss, minimizes switching losses, and maintains signal integrity by eliminating the need for transmit/receive switches, thereby enhancing the performance of secondary component carrier signals.
Implementation Method 1
a first time division duplex filter configured to process receive signals in the first frequency band and a second time division duplex filter configured to process transmit signals in the first frequency band
Implementation Method 2
the first time division duplex filter and the second time division duplex filter being implemented as a bulk acoustic wave (BAW) filter or a surface acoustic wave (SAW) filter
Implementation Method 3
the first time division duplex filter and the second time division duplex filter being implemented as a bulk acoustic wave (BAW) filter or a surface acoustic wave (SAW) filter
Data Source
AI summary
A carrier aggregation circuit that includes a primary signal path for processing a first frequency band, the first frequency band being a TDD frequency band, and a secondary signal path for processing a second frequency band. The primary signal path includes a first TDD filter configured to process receive signals in the first frequency band and a second TDD filter configured to process transmit signals in the first frequency band, the first TDD filter and the second TDD filter including one or more corresponding initial stages that are identical. Related front-end architectures, front-end modules, and wireless devices for carrier aggregation are also provided.