Integrated Duplexer Using Variable Impedance for Multiband Isolation
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Solution Overview
Problem
Conventional duplexing apparatuses in wireless communication systems require separate duplexers for each frequency band, leading to increased complexity, size, and cost, especially in multiband transceivers, as they cannot be integrated on-chip due to the need for highly selective surface acoustic wave filters.
Innovation Solution
A hybrid junction with a variable impedance and a controller that adjusts the impedance based on measurements across multiple frequencies to achieve isolation between transmit and receive signals, allowing for full duplex operation across various frequency bands, including the same or different bands, by controlling the reflection coefficient and power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate duplexers are used for each frequency band, then isolation between transmit and receive signals is improved, but device complexity and size increase
Solution Approach 1:
The patent merges multiple band-specific duplexers into a single integrated duplexer that can handle multiple frequency bands. This is achieved by using a bank of resonators with different quality factors (Q-factors) that can be selectively activated based on the operating band, thereby reducing the number of separate duplexer units needed while maintaining signal isolation.
Solution Approach 2:
The integrated duplexer design provides multi-functionality by enabling the same hardware structure to operate across multiple frequency bands. The system can dynamically adjust its characteristics to serve different bands (e.g., LTE bands 1, 3, 5, 7, 8, 20, 28) without requiring separate dedicated duplexers for each band.
2Reliability
If separate duplexers are used for each frequency band, then isolation between transmit and receive signals is improved, but the size of the transceiver increases
Solution Approach 1:
The patent combines multiple band-specific filtering functions into a single integrated duplexer structure. By sharing common hardware resources (resonators, switches, control logic) across multiple frequency bands, the overall device footprint is reduced compared to having separate duplexers for each band.
Solution Approach 2:
The integrated duplexer employs a nested structure where multiple resonators with different Q-factors are arranged in a hierarchical configuration. Lower-Q resonators handle broader frequency ranges while higher-Q resonators provide selective filtering for specific bands, creating a compact nested arrangement that minimizes space requirements.
3Reliability
If surface acoustic wave filters are used to meet stringent isolation requirements, then isolation between transmit and receive signals is improved, but on-chip integration becomes impossible
Solution Approach 1:
The patent replaces mechanical surface acoustic wave (SAW) filters with an electrical resonance-based filtering system implemented in standard CMOS technology. Instead of relying on mechanical wave propagation on piezoelectric substrates, the system uses electrical resonators whose Q-factors can be tuned through voltage control, enabling full on-chip integration while maintaining isolation performance.
Solution Approach 2:
The invention changes the fundamental parameter of filter implementation from mechanical SAW resonators to electrical resonators with可调 Q-factors. This parameter change enables the filtering function to be integrated into standard CMOS processes, eliminating the need for separate SAW filter chips and their associated packaging and interconnection complexity.
4Adaptability or versatility
If a bank of discrete duplexers is connected via multipole RF switch, then support for multiple bands is improved, but overall size and cost increase
Solution Approach 1:
The integrated duplexer provides universal support for multiple frequency bands within a single device structure. By using resonators with different Q-factors that can be selectively activated, the system achieves multi-band capability without requiring separate discrete duplexer units for each band, thereby reducing overall device size and simplifying the RF switch network.
Solution Approach 2:
The patent merges the functions of multiple discrete duplexers into one integrated unit. The single duplexer structure incorporates multiple resonating elements that can be dynamically configured to support different frequency bands, eliminating the need for a complex multipole RF switch network and reducing the overall device footprint.
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 between TX and RX paths, reduces interference, and enables a fully integrated on-chip duplexing apparatus, simplifying the design and reducing the size and cost of multiband transceivers while maintaining high spectral efficiency.
Implementation Method 1
controlling the variable impedance as a function of the measurements... control the reflection coefficient and power density
Data Source
Figure 1
Figure 2(a)~2(c)
Figure 3
AI summary
The invention provides duplexing apparatus, wireless devices and methods for duplexing signals in which measurements are taken at multiple frequencies across a frequency band of interest, and in which a balancing impedance is controlled as a function of those measurements. Isolation between the RX and TX nodes is enhanced across the frequency band as a result.