Near-field resonant coupled antenna structure for impedance matching
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Solution Overview
Problem
Conventional methods for coupling high-frequency electromagnetic signals from a chip to an off-chip antenna are inefficient due to silicon's high dielectric constant and low resistivity, leading to significant power loss in substrate modes and increased packaging costs.
Innovation Solution
A near-field resonant coupled antenna structure is used, comprising resonant loops on both the chip and an off-chip element, with a low loss dielectric like air or vacuum between them, to achieve strong resonance and efficient power transfer, reducing the impact of dimensional variations and parasitic inductance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wirebond or flip-chip technologies are used to couple electromagnetic energy from chip to off-chip antenna, then connection is established, but parasitic inductance causes large impedance mismatch at high frequencies
Solution Approach 1:
The patent extracts the resonant coupling function from the traditional wirebond/flip-chip connection structure. By placing resonant structures directly on the chip surface rather than relying on bond wire geometry, the design separates the connection function from the resonant coupling function, enabling high-frequency operation without parasitic inductance penalties
Solution Approach 2:
The patent changes the operating parameters by designing resonant structures with specific inductance and capacitance values that resonate at the target frequency. This transforms the connection from a passive inductive element to an active resonant element that can cancel parasitic inductance and achieve impedance matching at high frequencies
2Loss of energy
If on-chip ground shield is placed close to on-chip antenna to isolate from lossy substrate, then substrate mode coupling is reduced, but radiation efficiency drops to around 1%
Solution Approach 1:
The patent introduces an air cavity as an intermediary layer between the on-chip antenna and the lossy silicon substrate. This air gap acts as a mediator that prevents direct coupling between the antenna and substrate modes while maintaining sufficient isolation, thereby preserving radiation efficiency without requiring a close ground shield
Solution Approach 2:
The patent replaces the traditional electromagnetic shielding approach (using conductive ground planes) with a structural isolation approach (using air cavity and low-loss dielectric layers). This substitution eliminates the need for close ground shields that would short the antenna, allowing the antenna to radiate efficiently while still isolating from substrate losses
3Adaptability or versatility
If silicon substrate with high dielectric constant and low resistivity is used for on-chip antennas, then integration is achieved, but most antenna output power is coupled into substrate modes
Solution Approach 1:
The patent segments the electromagnetic field distribution by creating an air cavity beneath the antenna that confines the fields primarily in the air region rather than allowing them to penetrate into the lossy silicon substrate. This segmentation of the electromagnetic environment reduces substrate mode coupling while maintaining integration benefits
Solution Approach 2:
The patent creates a composite structure combining silicon substrate with air cavity and low-loss dielectric layers. This composite approach leverages the advantages of silicon (integration, mechanical support) while compensating for its disadvantages (losses, substrate modes) by introducing low-loss materials in strategic locations
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 approach significantly enhances radiation efficiency and reduces packaging costs by minimizing power loss in substrate modes and impedance mismatch, making it a more efficient and cost-effective method for coupling microwave, millimeter wave, and sub-millimeter wave signals.
Implementation Method 1
A near-field resonant coupled antenna structure is used, comprising resonant loops on both the chip and an off-chip element, with a low loss dielectric like air or vacuum between them, to achieve strong resonance and efficient power transfer
Data Source
AI summary
The invention relates to an antenna structure for coupling electromagnetic energy between a chip and an off-chip element, including a first resonant structure disposed on or in a chip. The first resonant structure is configured to have a first resonant frequency. The antenna structure also includes a second resonant structure disposed on or in an off-chip element. The second resonant structure is configured to have a second resonant frequency substantially the same as the first resonant frequency. The first resonant structure and the second resonant structure are mutually disposed within a near field distance of each other to form a coupled antenna structure that is configured to couple electromagnetic energy between the chip and the off-chip element. The electromagnetic energy has a selected wavelength in a wavelength range from microwave to sub-millimeter wave. The invention also relates to a method of calculating dimensions for a highly coupled antenna structure.