Split Band Duplexer Architecture for Multi-Mode RF Isolation
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Solution Overview
Problem
Existing RF duplexers face challenges in providing minimal insertion loss and adequate isolation between transmit and receive signals, especially in multi-mode and multi-band wireless communications systems with narrow duplex gaps, due to manufacturing tolerances and environmental factors.
Innovation Solution
The RF circuitry employs a split band duplexer architecture that separates the FDD receive and transmit bands into sub-bands, allowing for the use of standard filter components like SAW filters, and includes power directing and switching circuitry to manage different operating modes, ensuring optimal band separation and isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a duplexer is used to provide transmit and receive passbands with minimal insertion loss, then signal loss is reduced, but providing required isolation between transmit and receive signals becomes difficult when duplex gaps are narrow
Solution Approach 1:
The duplexer architecture is segmented into multiple independent filter banks, each handling specific frequency bands. The transmit path includes a transmit filter bank with multiple bandpass filters, and the receive path includes a receive filter bank with multiple bandpass filters. This segmentation allows each filter to be optimized for its specific band, achieving minimal insertion loss while maintaining isolation through the bank structure.
Solution Approach 2:
Switching circuitry acts as an intermediary between the antenna and the filter banks, dynamically connecting the antenna to either the transmit or receive path based on operational mode. This intermediary component enables the system to achieve both transmit and receive isolation by physically separating the signal paths when needed, while allowing minimal insertion loss during active transmission or reception.
2Device complexity
If multi-mode and multi-band wireless systems use common circuit elements to reduce size and cost, then device complexity is reduced, but providing required isolation and minimal insertion loss across all modes becomes more difficult
Solution Approach 1:
The duplexer architecture uses universal filter banks that can operate across multiple frequency bands and modes. Each filter bank is designed to handle multiple bands, and the switching circuitry can configure the same physical components to serve different operational modes (TDD, FDD, half-duplex). This multi-functionality reduces the need for separate dedicated components for each mode while maintaining isolation and insertion loss performance.
Solution Approach 2:
The system employs dynamic switching circuitry that can reconfigure the filter banks and signal paths in real-time based on the operational mode and frequency band being used. This dynamic reconfiguration allows the same physical components to adapt to different modes (TDD, FDD, half-duplex) and bands, maintaining optimal isolation and insertion loss characteristics for each configuration without requiring separate static components for each mode.
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 solution enhances isolation margins and reduces insertion loss, enabling efficient operation across various modes and bands while relaxing design constraints, thus supporting multi-mode and multi-band wireless systems effectively.
Implementation Method 1
The transmit filter bank includes a first surface acoustic wave (SAW) filter
Data Source
AI summary
Radio frequency (RF) circuitry, which includes a time division duplex (TDD)/frequency division duplex (FDD) driver stage, a TDD final stage, an FDD final stage, and power directing circuitry, is disclosed. The power directing circuitry is coupled between the TDD/FDD driver stage and the TDD final stage, and is further coupled between the TDD/FDD driver stage and the FDD final stage.