ESD Protection Circuit Redundant Capacitor Segmentation
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Solution Overview
Problem
Integrated circuits in implantable medical devices are vulnerable to electrostatic discharge (ESD) events, which can cause time-dependent dielectric breakdown of capacitors, leading to premature device failure and battery depletion, due to the lack of effective redundancy in existing ESD protection circuits.
Innovation Solution
Incorporating an array of capacitors in series, parallel, or series-parallel configurations within the ESD protection circuit to provide redundancy and prevent failures such as short circuits, open circuits, or leakage, thereby ensuring reliable operation during ESD events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single capacitor is used in the ESD protection circuit, then the device complexity is reduced, but the reliability deteriorates due to time-dependent dielectric breakdown
Solution Approach 1:
The single capacitor is segmented into multiple capacitors (first capacitor and second capacitor) connected in series. This segmentation provides redundancy such that if one capacitor fails due to time-dependent dielectric breakdown, the other capacitor can continue to provide ESD protection, thereby improving reliability while maintaining manageable circuit complexity
Solution Approach 2:
The series connection of multiple capacitors acts as a beforehand cushioning mechanism against capacitor failure. The redundant capacitor is prepared in advance to compensate for potential failures, ensuring continuous ESD protection even when one capacitor degrades or fails over time
2Reliability
If a higher working voltage is applied across the capacitor, then the ESD protection effectiveness is improved, but the time-dependent dielectric breakdown occurs more rapidly
Solution Approach 1:
The voltage stress is segmented across multiple series-connected capacitors. Each capacitor experiences a portion of the total working voltage rather than the full voltage, which reduces the rate of time-dependent dielectric breakdown for each individual capacitor while maintaining effective ESD protection at the circuit level
Solution Approach 2:
The voltage parameter is changed from a single high-voltage capacitor to multiple lower-voltage capacitors in series. This parameter change distributes the electrical stress, extending the operational lifetime of each capacitor by reducing the voltage-induced degradation rate while preserving the overall 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 redundant capacitor configurations effectively mitigate the risk of capacitor failures, ensuring reliable ESD protection and preventing unwanted battery depletion in implantable medical devices by maintaining specified voltage ratings and frequency ranges.
Implementation Method 1
An ESD protection circuit can include an active device, such as a transistor, and a sensing circuit, such as including a resistor and a capacitor
Implementation Method 2
Electrostatically-stored energy, when discharged, can damage integrated circuits such as via electrically overstressing devices included in such circuits
Data Source
AI summary
An implantable medical device can include an integrated circuit comprising an electrostatic discharge (ESD) protection circuit. The ESD protection circuit can include an active circuit, a first passive circuit, and a second passive circuit. For example, at least one of the first or second passive circuits can include an array of capacitors in a series configuration, a parallel configuration, or a combination of series and parallel configurations. The first and second passive circuits can be configured to establish a specified time constant, and, in response to an applied ESD, the first and second passive circuits can provide a control signal to active circuit to switch the active circuit from a substantially non-conductive mode to a substantially conductive mode.