Directional Coupler Miniaturization via Dynamic Termination
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Solution Overview
Problem
Miniaturization of directional couplers in wireless communication devices is hindered by the need for specific microstrip line lengths to maintain desired coupler characteristics, making it challenging to reduce line length while ensuring effective signal processing.
Innovation Solution
A signal processing circuit with a directional coupler and a control unit that adjusts the connection of termination parts and switches based on RF signal frequency, allowing for arbitrary microstrip line lengths by optimizing the phase and path of coupling signals through various devices and components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the line length of the microstrip line is reduced to miniaturize the directional coupler, then the device size is reduced, but the coupler characteristics cannot be ensured
Solution Approach 1:
The patent applies dynamics by making the termination impedance adjustable and switchable depending on the frequency band. The control unit switches between different termination impedances (e.g., 50Ω for low band, 0Ω for high band) to optimize coupler characteristics across different frequencies, enabling the use of shorter microstrip lines while maintaining performance.
Solution Approach 2:
The patent changes the termination impedance parameter based on frequency requirements. By switching termination impedances between different values (50Ω, 0Ω, or other values) depending on whether the operating frequency is in the low band or high band, the system achieves desired coupler characteristics with reduced line lengths.
2Volume of moving object
If the line length of the microstrip line is reduced, then the device size is reduced, but the directivity of the coupler deteriorates
Solution Approach 1:
The patent uses dynamic switching of termination impedances to maintain high directivity across different frequency bands. The control unit adjusts the termination impedance based on the operating frequency, ensuring that the phase relationship between coupling and isolation signals remains optimal for achieving high directivity even with shorter line lengths.
Solution Approach 2:
By changing the termination impedance parameter according to frequency requirements, the patent maintains the phase opposition between return signals and isolation signals, thereby preserving directivity performance while allowing for miniaturization of the coupler structure.
3Device complexity
If a fixed termination impedance is used, then the circuit structure is simple, but the coupler characteristics cannot be optimized across different frequency bands
Solution Approach 1:
The patent implements multi-functionality by making the termination impedance adaptable to different frequency bands. The termination circuit can switch between multiple impedance values (50Ω for low band, 0Ω for high band, or other values) to optimize coupler characteristics across various operating frequencies, making the coupler universally applicable to different frequency requirements.
Solution Approach 2:
The termination impedance is made dynamic rather than fixed, allowing the system to adapt to different frequency bands. The control unit switches between different termination configurations based on the operating frequency, enabling the same coupler structure to perform optimally across multiple frequency ranges.
Data Source
AI summary
In one example, a signal processing circuit including a directional coupler and a termination part is disclosed. The directional coupler includes a main line as a transmission path of an RF signal and a sub-line constituting a coupled line together with the main line. The termination part includes devices connectable between ground and a first port at an end of the sub-line. The signal processing circuit switches, depending on a frequency of the RF signal, the devices of the termination part to be connected to the first port. The phase of a return signal of a signal input as a coupling signal to the termination part via the first port is opposite to the phase of an isolation signal supplied to a second port at the other end of the sub-line and connected to an output port of the coupling signal.