Filter Circuit Substrate Layout for Parasitic Inductance Cancellation
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Solution Overview
Problem
Existing filter circuits with capacitance elements face issues with noise suppression due to parasitic inductance, leading to decreased charge supplying performance to electronic components, especially when using impedance conversion circuits or coils to cancel parasitic inductance.
Innovation Solution
A circuit substrate design that incorporates a capacitance element with additional inductance elements and a capacitance structure, where the capacitance provided by the output terminal and a second electrode is equal to or greater than the capacitance of the capacitance element, allowing for effective cancellation of parasitic inductance and maintenance of charge supplying performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a capacitor is used in a filter circuit, then noise suppression is achieved, but parasitic inductance decreases noise suppression effect
Solution Approach 1:
The patent introduces an impedance conversion circuit that converts the parasitic inductance of the capacitor into a useful negative capacitance effect. The circuit uses the harmful parasitic inductance to create a pseudo-negative capacitance that counteracts the parasitic inductance's negative impact on noise suppression, thereby converting the harmful factor into a beneficial one for improving filter performance
Solution Approach 2:
The patent employs an impedance conversion circuit as an intermediary between the capacitor and the filter circuit. This intermediary circuit transforms the capacitor's parasitic inductance characteristics into a form that can be effectively utilized for noise suppression, mediating the conflict between the capacitor's filtering function and its parasitic inductance
2Object-affected harmful factors
If an impedance conversion circuit is used to cancel parasitic inductance, then noise suppression improves, but charge supplying performance decreases
Solution Approach 1:
The patent applies local quality by designing the impedance conversion circuit with specific local characteristics that differ from the main capacitor. The circuit includes resistors and capacitors with carefully selected values to create a localized impedance transformation that cancels parasitic inductance only in the frequency range where it matters for noise suppression, while maintaining charge supplying performance at lower frequencies
Solution Approach 2:
The patent utilizes parameter changes by adjusting the resistance and capacitance values in the impedance conversion circuit to optimize the cancellation of parasitic inductance. By changing these parameters, the circuit can be tuned to achieve effective parasitic inductance cancellation at specific frequency ranges while preserving the capacitor's ability to supply charge rapidly when needed
3Object-affected harmful factors
If a coil is used to cancel parasitic inductance, then noise suppression improves, but charge supply timing is delayed
Solution Approach 1:
The patent replaces the mechanical/physical coil-based inductance cancellation approach with an electronic impedance conversion circuit. Instead of using a physical coil to counteract parasitic inductance, the circuit uses combinations of resistors and capacitors to achieve the same effect through impedance transformation, eliminating the time delay associated with inductive elements while maintaining noise suppression benefits
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 effectively cancels parasitic inductance, improving noise reduction in high-frequency bands while ensuring stable charge supply to electronic components, preventing delays and maintaining performance even under voltage drops.
Implementation Method 1
the parasitic inductance of a capacitor cannot be cancelled sufficiently even when the impedance conversion circuit is used as a filter circuit
Implementation Method 2
the electric charge of the capacitor is able to be supplied to the electronic component even when a voltage drop occurs
Data Source
AI summary
A circuit substrate includes a first electrode connecting a capacitance element, a first inductance element including a first interconnect that extends from one end connected to the first electrode to another end across a region at which the capacitance element is to be mounted, a second inductance element including a second interconnect that extends from one end connected to the first electrode to another end across the region at which the capacitance element is to be mounted from a side opposite to the first interconnect, an input terminal connected to the another end of the second interconnect, an output terminal connected to the another end of the first interconnect, and a second electrode that provides a capacitance between the output terminal and the second electrode, wherein the capacitance provided by the output terminal and the second electrode is equal to or larger than a capacitance of the capacitance element.