High-Frequency Circuit Device Parasitic Oscillation Suppression
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Solution Overview
Problem
High-frequency circuit devices handling terahertz waves face challenges in suppressing parasitic oscillations due to increased impedance at frequencies above 10 MHz, which is difficult to control with conventional lumped constant circuits.
Innovation Solution
The implementation of a capacitive structure within the package substrate, comprising a shunt path, package signal conductor, and package ground, which includes a series connection of resistance and capacitance elements, helps to reduce impedance and suppress parasitic oscillations across a wide frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shunt element with resistance and capacitance is electrically connected in parallel to the voltage bias circuit, then parasitic oscillation is suppressed, but the impedance increases at frequencies above 10 MHz making control difficult
Solution Approach 1:
The patent transitions from a two-dimensional surface mounting approach to a three-dimensional vertical structure by forming the capacitive element within the thickness direction of the package substrate. The first electrode is formed on the upper surface, the second electrode on the lower surface, creating a vertical capacitor that reduces horizontal space requirements and allows better integration with the shunt path.
Solution Approach 2:
The capacitive element is nested within the package substrate structure itself, utilizing the substrate's thickness to accommodate the capacitor. The insulating layer is formed inside the substrate, with electrodes on opposite surfaces, effectively nesting the capacitive function within the existing package structure rather than adding external components.
2Device complexity
If conventional lumped constant circuits are used, then circuit simplicity is maintained, but impedance control above 10 MHz becomes difficult and parasitic oscillation cannot be effectively suppressed
Solution Approach 1:
The patent introduces a specifically designed capacitive element as an intermediary component between the shunt path and ground. This capacitor acts as a mediator that modifies the impedance characteristics of the shunt path, enabling effective parasitic oscillation suppression without requiring complex active circuitry. The capacitor value is carefully selected to provide the necessary impedance transformation.
Solution Approach 2:
The patent changes the physical parameters of the package substrate structure to achieve the desired electrical characteristics. By controlling the thickness of the insulating layer, the area of electrodes, and the dielectric constant of the insulating material, the capacitance value is optimized to provide appropriate impedance matching and parasitic oscillation suppression in the medium frequency range.
3Ease of manufacture
If the shunt path is formed on the upper surface with conventional elements, then manufacturing is simplified, but the capacitive structure cannot be effectively integrated to reduce impedance
Solution Approach 1:
The patent merges the capacitive element formation process with the existing package substrate manufacturing process. The insulating layer is formed as part of the substrate structure, and the electrodes are integrated during the same fabrication sequence, combining the capacitor creation with the substrate packaging operations rather than requiring separate assembly steps.
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 configuration effectively stabilizes the high-frequency circuit device by reducing impedance and suppressing parasitic oscillations, particularly in the medium frequency range, thereby enhancing the device's operational stability.
Implementation Method 1
a part of the base, a part of the shunt path, and the package second ground constitute a capacitive structure
Data Source
AI summary
A high-frequency circuit device includes: a chip which includes a high-frequency element, a high-frequency circuit, a signal conductor, and a chip ground; a package substrate on which the chip is disposed, a shunt path which is constituted by a package signal conductor which is disposed on an upper surface of the package substrate and is electrically connected to the signal conductor, a package first ground which is electrically connected to the chip ground, and a shunt element which is electrically connected to the package signal conductor and the package first ground; and a package second ground which is disposed at least inside the base of the package substrate or on a back surface of the package substrate, wherein a part of the base, a part of the shunt path, and the package second ground constitute a capacitive structure.