Thin-Oxide Transistor Segmentation for High-Voltage Neurostimulation
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Solution Overview
Problem
Conventional neurostimulation systems face challenges in safely handling high voltage signals due to the risk of damaging oxide layers in transistors, particularly in pulse generating circuitry used in implantable medical devices like pacemakers and neurostimulation systems.
Innovation Solution
The implementation of thin-oxide transistors with drain extensions and multi-domain voltage control circuitry that maintains the gate-to-source voltage within a safe range, using programmable switches and voltage multipliers to generate and manage anode and cathode voltages, prevents oxide layer damage and enables efficient high voltage signal switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional transistors with thick oxide layers are used in pulse generating circuitry, then the transistors are protected from damage, but the ability to safely switch high voltage signals up to 20V is limited
Solution Approach 1:
The transistor gate oxide is segmented into thin and thick regions, with the thin oxide region enabling high voltage signal switching and the thick oxide region providing protection. This segmentation allows the transistor to handle high voltage signals up to 20V while maintaining reliability through the protective thick oxide structure.
Solution Approach 2:
Different regions of the transistor gate oxide have different thicknesses to perform different functions. The thin oxide region under the gate electrode provides high voltage switching capability, while the thick oxide region at the edges provides protection against damage, creating local quality variations that resolve the contradiction.
2Adaptability or versatility
If thin oxide transistors are used to enable high voltage switching, then the ability to generate stimulation pulses with high voltage signals is improved, but the risk of oxide layer damage increases
Solution Approach 1:
The gate oxide is segmented with thin and thick regions, allowing the thin region to enable high voltage switching while the thick region protects against damage. This segmentation resolves the contradiction by distributing different functions to different parts of the structure.
Solution Approach 2:
The thick oxide region acts as a pre-established protective cushion that prevents damage to the thin oxide region during high voltage operation. This beforehand protection allows the thin oxide to perform high voltage switching without risking damage.
3Adaptability or versatility
If voltage multiplier circuitry is added to generate high anode voltages, then the stimulation pulse voltage capability is improved, but the device complexity increases
Solution Approach 1:
The voltage multiplier circuitry is integrated into the pulse generating circuitry to perform multiple functions: generating high anode voltages for stimulation pulses, providing voltage multiplication for the transistor gates, and enabling programmable voltage selection. This multi-functionality reduces the need for separate high voltage generation circuits.
Solution Approach 2:
The voltage multiplier circuitry is merged with the pulse generating circuitry and transistor control circuitry into a single integrated system. This combining of functions reduces overall device complexity while maintaining the ability to generate high voltage stimulation pulses.
Data Source
AI summary
In one embodiment, a method, of operating an IPG, comprises: generating a variable anode voltage by first circuitry to drive current during pulse generation, the first circuitry being programmable to generate the anode voltage from a plurality of voltages in response to a control signal; providing the anode voltage to a first circuit node; operating a transistor to control current flow between the first circuit node and an output of the IPG, wherein the transistor possesses a gate-to-source breakdown voltage; generating a first supply signal that is maintained at a voltage level equal to the anode voltage plus or minus a predetermined amount; and selectively applying the first supply signal and a second supply signal to a gate of the transistor to connect or disconnect the first circuit node in a circuit path with the output of the IPG.