RF Module FDD TDD Isolation Matching Circuit
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Solution Overview
Problem
The existing radio frequency front-end circuits in mobile communication devices suffer from degraded receiver sensitivity in FDD signal paths due to unwanted waves from transmit power amplifiers coupling into receive low noise amplifiers via TDD signal paths.
Innovation Solution
A radio frequency module configuration that includes separate transmit and receive filters for FDD and TDD communication bands, power amplifiers, low noise amplifiers, and impedance matching circuits, with specific component arrangements on a module board to minimize electromagnetic coupling between matching circuits, thereby reducing unwanted wave interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate transmit power amplifiers for FDD and TDD signal paths are used, then communication functionality for both FDD and TDD bands is improved, but unwanted waves from the transmit power amplifier couple into the receive low noise amplifier via the TDD signal path, degrading receiver sensitivity in the FDD signal path
Solution Approach 1:
The patent divides the radio frequency module into separate FDD and TDD signal paths with dedicated components. The FDD transmit path includes a first power amplifier and first impedance matching circuit, while the TDD transmit path includes a second power amplifier and second impedance matching circuit. This segmentation isolates the signal paths to prevent unwanted wave coupling between FDD and TDD bands, thereby maintaining receiver sensitivity while supporting both communication functionalities.
Solution Approach 2:
The patent introduces impedance matching circuits as intermediary components between the power amplifiers and filters/antenna. The first impedance matching circuit is connected between the first power amplifier and the first transmit filter, while the second impedance matching circuit is connected between the second power amplifier and the second transmit filter. These intermediary matching circuits provide isolation and impedance transformation that prevent unwanted waves from coupling into the receive path, thus protecting receiver sensitivity.
2Productivity
If different transmit power amplifiers are used for FDD and TDD signal paths, then signal transmission for both communication bands is improved, but coupling between output matching circuits causes unwanted waves to flow into the receive low noise amplifier, degrading receiver sensitivity
Solution Approach 1:
The patent applies local quality by providing dedicated impedance matching circuits specifically for each power amplifier output. The first impedance matching circuit is locally connected to the first power amplifier output, and the second impedance matching circuit is locally connected to the second power amplifier output. Each matching circuit is optimized for its specific signal path, providing localized impedance transformation and isolation that prevents unwanted wave interference while maintaining signal transmission quality.
Solution Approach 2:
The patent extracts the impedance matching function into separate, dedicated circuits for each power amplifier. Rather than using a shared matching circuit that could cause coupling, the first impedance matching circuit is extracted and dedicated to the FDD transmit path, while the second impedance matching circuit is extracted and dedicated to the TDD transmit path. This extraction isolates the matching functions and prevents unwanted wave coupling between paths.
Data Source
AI summary
A radio frequency module includes a transmit filter that allows a transmit signal of a band A for FDD to pass through, a receive filter that allows a receive signal of the band A to pass through, a filter that allows a transmit/receive signal of a band B for TDD to pass through, power amplifiers, a low noise amplifier, a switch between connecting the receive filter to the low noise amplifier and connecting the filter to the low noise amplifier, a switch between connecting the filter to the power amplifier and connecting the filter to the low noise amplifier, a matching circuit connected between the power amplifier and the transmit filter, a matching circuit connected between the power amplifier and the switch, and a module board. On the module board, each of the power amplifiers and the switch is arranged in between the matching circuit and the matching circuit.