Integrated Low-Pass Filter with Varistors for ESD Protection
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Solution Overview
Problem
Existing low-pass filters with ESD protection functions have a large mounting area due to the size of coil components, capacitors, and zener diodes, which limits packaging density.
Innovation Solution
A low-pass filter design incorporating a capacitor with internal electrodes, varistors, and a resistor arranged in a π-type RC configuration on a single chip, where varistors are connected in parallel with capacitors and the resistor is connected to internal electrodes, enhancing packaging density while providing ESD protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If zener diodes are used for ESD protection in low-pass filters, then ESD protection function is achieved, but mounting area increases due to large component size and height
Solution Approach 1:
The patent combines multiple discrete components (capacitors, varistors, resistors) into a single integrated low-pass filter module. The varistors are mounted on the same substrate as the π-type filter components, with their electrodes connected to corresponding filter nodes. This integration eliminates the need for separate ESD protection components, reducing overall mounting area while maintaining ESD protection functionality through the varistor elements.
2Reliability
If discrete components are mounted separately, then ESD protection function is achieved, but packaging density decreases
Solution Approach 1:
The invention merges the ESD protection function with the low-pass filter structure by integrating varistors directly onto the filter substrate. The varistors share the same mounting area as the filter components, and their electrical connections are made through the existing substrate trace network. This approach achieves both ESD protection and high packaging density within a single compact module.
Solution Approach 2:
The substrate serves multiple functions: it provides mechanical support for the π-type filter components, establishes electrical connections between components through trace networks, and mounts the varistors for ESD protection. This multi-functional substrate design enables a single component to fulfill multiple roles, improving packaging density while maintaining ESD protection capability.
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 design achieves improved packaging density and ESD protection by integrating varistors and resistors on the same chip as capacitors, reducing the overall size and enhancing mechanical strength, and allowing for more compact and cost-effective ESD protection compared to zener diodes.
Implementation Method 1
a capacitor including a dielectric body having first and second faces opposing each other, and first to third internal electrodes arranged within the dielectric body
Implementation Method 2
a capacitor including a dielectric body having first and second faces opposing each other
Implementation Method 3
a first varistor layer including a region positioned between the first and second electrodes and exhibiting a nonlinear current-voltage characteristic
Data Source
AI summary
A low-pass filter comprises a capacitor, first and second varistors, a resistor, and first to third external electrodes. The capacitor includes a dielectric body and first to third internal electrodes. The first internal electrode is connected to the third external electrode physically and electrically. The second internal electrode is connected to the second external electrode physically and electrically. At least a portion of the second internal electrode opposes the first internal electrode through at least a portion of the dielectric body. The third internal electrode is connected to the first external electrode physically and electrically. At least a portion of the third internal electrode opposes the first internal electrode through at least a portion of the dielectric body. The first varistor is connected in parallel to a capacitor constituted by the first and third internal electrodes. The second varistor is connected in parallel to a capacitor constituted by the first and second internal electrodes. The resistor is connected electrically to the second and third internal electrodes.