RF Front-End Module Band Isolation via Diplexer Segmentation
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Solution Overview
Problem
Current RF front-end modules suffer from reduced sensitivity due to undesired interference (intermodulation products) when operating in 4G/5G dual mode, particularly in ENDC operation, leading to desense issues, which existing solutions like increased transmitter linearity, notch filters, and separate modules either increase current consumption or circuit board area and cost.
Innovation Solution
The implementation of a pair of diplexers that filter different RF bands, providing physical separation between transmitters and receivers, and using band-pass filters to isolate intermodulation products, reducing their propagation path and thus desense without increasing current consumption or module size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If separate modules are used for each transmitter to improve isolation and reduce IMD products, then intermodulation product isolation is improved, but circuit board area and manufacturing cost increase significantly
Solution Approach 1:
The single RF front-end module is segmented into distinct functional zones: a first transceiver unit (TX1/RX1) and a second transceiver unit (TX2/RX2), with each unit containing its own transmitter, receiver, and diplexer. This internal segmentation provides isolation between transmitters while maintaining a compact integrated form factor, avoiding the need for separate physical modules.
Solution Approach 2:
Multiple transceiver units are nested within a single integrated RF front-end module housing. Each transceiver unit is self-contained with its own diplexer and filtering elements, creating a nested structure that provides isolation equivalent to separate modules while occupying the space of a single module on the circuit board.
2Object-generated harmful factors
If transmitter linearity is increased to reduce IMD product generation, then intermodulation product level is reduced, but current consumption increases
Solution Approach 1:
Diplexers with band-pass filters are introduced as intermediary elements between the transmitters and antennas/receivers. These diplexers selectively pass desired frequency bands while attenuating intermodulation products, achieving IMD reduction without requiring increased transmitter linearity and thus avoiding additional current consumption.
Solution Approach 2:
The harmful intermodulation products are extracted and removed from the signal path using diplexer-based band-pass filters. Instead of preventing IMD generation at the transmitter, the solution extracts and filters out the IMD products after generation, maintaining low current consumption while achieving desense reduction.
3Object-generated harmful factors
If notch filters are used to reject unwanted transmitter leakage, then transmitter leakage is reduced, but loss at wanted frequencies increases requiring more transmit power and current
Solution Approach 1:
Diplexers serve as intermediary filtering elements that provide selective frequency transmission. Unlike notch filters that create narrow rejection bands causing collateral loss, diplexers use broad band-pass characteristics to reject transmitter leakage while maintaining high transmission efficiency for desired signals, avoiding the need for increased transmit power.
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 configuration significantly reduces receiver desense by providing higher isolation for intermodulation products, improving sensitivity without increasing power consumption or circuit board space, and is scalable for multiple bands.
Implementation Method 1
a first diplexer to the first transmitter and the first receiver, and the first receiver configured to receive at the second RF band. The second antenna is connected via a second diplexer to the second transmitter and the second receiver
Data Source
AI summary
An RF front-end module including a first transceiver unit, a second transceiver unit, a first antenna, a second antenna, a first diplexer, and a second diplexer. The first transceiver unit has a first transmitter and a first receiver and is configured to transmit at a first LTE 4G band, and the second transceiver unit has a second transmitter and a second receiver and is configured to transmit at a first new radio 5G (NR) band. The first antenna is connected via the first diplexer to the first transmitter and the first receiver, the first receiver being configured to receive at the first new radio 5G band, and the second antenna is connected via the second diplexer to the second transmitter and the second receiver, the second receiver being configured to receive at the first LTE 4G band.