RF IC Device Impedance Matching via Annular Electrode
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Solution Overview
Problem
Conventional RFID systems face challenges in achieving impedance matching over a wide frequency band and maintaining desired radiation characteristics, which limits their ability to perform both long-distance and short-distance communication effectively, especially due to variations in manufacturing and impedance differences between IC chips and antennas.
Innovation Solution
A radio frequency IC device with a resonant circuit-based feed circuit that supports various impedances, featuring an annular electrode coupled to a dipole radiation plate, allowing for improved signal radiation characteristics and enabling both long-distance and short-distance communication using magnetic-field and electric-field radiation plates, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only an inductance unit is used for impedance matching between the LSI chip and the dipole antenna, then the device structure is simple, but the frequency range for impedance matching is narrow and variations in manufacturing cause frequency instability
Solution Approach 1:
The patent combines capacitance units and inductance units to form a resonant circuit for impedance matching. This merging of different circuit elements (capacitors and inductors) creates a more robust matching network that can maintain stable frequency characteristics despite manufacturing variations, resolving the contradiction between structural simplicity and frequency stability.
Solution Approach 2:
The patent introduces capacitance units with specific capacitance values (e.g., 1000pF, 2200pF, 3300pF) that can be adjusted to optimize the resonant frequency and impedance matching characteristics. By changing the capacitance parameters, the system achieves broader frequency range matching and improved frequency stability without excessive structural complexity.
2Volume of moving object
If the size of the dipole antenna is reduced by forming wider regions at both ends, then the antenna size is reduced, but the signal radiation characteristics are degraded and the frequency range for desired radiation gain is narrowed
Solution Approach 1:
The patent adds a third dimension by stacking multiple antenna elements (first dipole antenna, second dipole antenna, and parasitic elements) vertically. This dimensional transition allows the system to maintain compact horizontal footprint while achieving desired radiation characteristics through spatial diversity and constructive interference of multiple radiating elements.
Solution Approach 2:
The patent employs a nested structure where parasitic elements are positioned between and around the active dipole antennas. These nested parasitic elements contribute to the overall radiation pattern and impedance characteristics without significantly increasing the external dimensions, effectively packing multiple functional elements within a compact volume.
3Length of moving object
If the area where magnetic flux crosses is increased to enable short-distance communication, then the communication distance is extended, but the device area becomes larger
Solution Approach 1:
The patent uses thin film structures for the antenna elements and resonant circuits, allowing the magnetic flux to penetrate through the thin dielectric layers. This thin-film approach enables extended magnetic coupling distance without proportionally increasing the device area, as the flux can extend beyond the physical boundaries of the thin-film components.
Solution Approach 2:
The patent divides the antenna system into multiple segmented elements (first dipole antenna, second dipole antenna, parasitic elements) that can be independently optimized. This segmentation allows the magnetic flux distribution to be extended across multiple elements, achieving longer effective communication distance while maintaining a compact overall device footprint through efficient spatial arrangement.
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
The solution achieves desired radiation characteristics over a wide frequency range, enabling efficient long-distance and short-distance communication with reduced energy consumption and improved manufacturing simplicity by securing a large area for magnetic flux crossing, thus addressing the limitations of conventional RFID systems.
Implementation Method 1
a resonant circuit that adjusts impedance between the radio IC and the radiation plate
Implementation Method 2
an annular electrode that is electromagnetically coupled to a dipole radiation plate
Implementation Method 3
a magnetic-field radiation plate that allows short-distance communication with a reader/writer
Data Source
Figure 1(A)~1(C)
Figure 2~4
Figure 5
AI summary
An object is to provide a radio frequency IC device capable of achieving impedance matching between a radio IC chip and a radiation plate in a wide frequency band, and achieving desired radiation characteristics over a wide range of frequencies. Another object is to provide a radio frequency IC device and a radio communication system that allow both long-distance and short-distance communication and, in particular, allow short-distance communication using a small amount of energy. A radio frequency IC device includes an electromagnetic coupling module (1) having a radio IC chip (5) and a feed circuit board (10), and a radiation plate (15). An annular electrode (25) is disposed to be coupled to both a feed circuit of the electromagnetic coupling module (1) and the radiation plate (15). The radiation plate (15) serves as an electric-field radiation plate for long-distance communication, while the annular electrode (25) serves as a magnetic-field radiation plate for short-distance communication. The feed circuit board (10) may be removed, so that the radio IC chip (5) is coupled to the annular electrode (25) directly or with an interposer disposed therebetween.