Tunable Filter Attenuates Rx Noise in Multi-Band TxRx Modules
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Solution Overview
Problem
Existing transmission and reception modules in mobile communication terminals face challenges in maintaining a high signal-to-noise ratio due to noise leakage from transmission bands to reception bands, especially in narrow band frequency operations, where insufficient duplexer isolation and envelope tracking amplify reception band noise, degrading signal quality.
Innovation Solution
A transmission and reception module is designed with variable filters and switches that attenuate reception band noise by adjusting frequency bands, using tunable filters and power amplifiers to minimize noise interference between transmission and reception paths, and includes a harmonic variable filter to reduce harmonic overlap in carrier aggregation systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If envelope tracking is performed to optimize power added efficiency of the power amplifier, then power efficiency is improved, but reception band noise is generated from the DC-DC converter which further degrades the signal to noise ratio
Solution Approach 1:
A transmission variable filter is introduced as an intermediary component between the power amplifier and the antenna. This filter selectively attenuates reception band noise generated by the DC-DC converter during envelope tracking operations while allowing transmission signals to pass through, thus mediating between the power efficiency improvement and noise reduction requirements
2Device complexity
If the isolation characteristics of the duplexer are insufficient in narrow band frequency operations, then device complexity is reduced, but reception band noise leaks from the transmission band to the reception band degrading signal to noise ratio
Solution Approach 1:
The noise filtering function is segmented from the duplexer structure and implemented as a separate transmission variable filter. This segmentation allows the duplexer to maintain simpler isolation characteristics while the dedicated filter handles reception band noise attenuation, dividing the noise control function into independent manageable components
3Object-affected harmful factors
If a fixed filter is used to attenuate reception band noise, then noise attenuation is achieved, but the filter cannot adapt to different frequency bands reducing versatility
Solution Approach 1:
The transmission variable filter employs variable filtering elements that can dynamically adjust their characteristics based on the operating frequency band. This dynamic adjustment capability allows the filter to effectively attenuate reception band noise across multiple frequency bands including wide gap bands and narrow gap bands, maintaining versatility while achieving noise attenuation
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 effectively reduces the degradation of signal-to-noise ratio by attenuating reception band noise and harmonic interference, improving signal quality across various frequency bands and carrier aggregation scenarios.
Implementation Method 1
a transmission variable filter that varies a frequency band to attenuate reception band noise in the plurality of first frequency bands
Data Source
AI summary
Transmission paths correspond to frequency bands, respectively, and transmission signals of the four bands are transmitted through the transmission paths. Reception paths correspond to the frequency bands, respectively, and reception signals of the four bands are transmitted through the reception bands. A Tx switch selects a transmission path corresponding to one of the frequency bands so that a transmission signal corresponding to the frequency band is emitted from an antenna. An Rx switch selects a reception path corresponding to the frequency band so that a reception signal of the frequency band received by the antenna is extracted. A tunable filter is a filter whose frequency band is adjusted in a variable manner so that reception band noise of the frequency band is attenuated, and is provided between each of the antenna and the Rx switch, and the Tx switch.