Electrostatic Charge Sensor With High-Impedance Pads for Weak Fields
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Solution Overview
Problem
Electrostatic charge sensors suffer from current leakage due to shared contact pads with other electrical components, especially at higher temperatures, reducing sensitivity and making it difficult to measure weak electrostatic fields.
Innovation Solution
Implement high impedance contact pads by overcharging transistors of output drivers with pumped electrical signals to reduce current leakage, using positive and negative charge pumps and level shifters to maintain a high impedance state during measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If contact pads are shared with other electrical components, then device complexity is reduced, but current leakage increases
Solution Approach 1:
The patent changes the electrical parameter (impedance) of the contact pad from low to high by applying a negative voltage to the output driver transistor gates. This parameter change reduces current leakage while maintaining shared contact pad architecture, resolving the contradiction between device complexity and current leakage.
2Temperature
If temperature increases, then device operation continues, but current leakage increases
Solution Approach 1:
The patent applies preliminary anti-action by proactively applying a negative voltage to the output driver transistor gates before temperature-induced current leakage becomes problematic. This preemptive high-impedance state counteracts the temperature effect, maintaining measurement accuracy across temperature ranges.
3Reliability
If current leakage increases, then contact pad connectivity is maintained, but measurement precision decreases
Solution Approach 1:
The patent implements dynamic control of the output driver transistor gates by applying negative voltage only during electrostatic field measurements. This dynamic approach maintains contact pad connectivity when needed while achieving high impedance during measurements, thereby preserving both reliability and measurement precision.
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 electrostatic charge sensor achieves high sensitivity and can detect weak electrostatic fields by minimizing current leakage through the use of high impedance contact pads, ensuring accurate measurements even in high-temperature environments.
Implementation Method 1
overcharging transistors of the output drivers with pumped electrical signals
Implementation Method 2
contact pads are set to a high impedance state by overcharging transistors
Data Source
Figure 1
Figure 2~3
AI summary
A device provides high impedance contact pads (14) for an electrostatic charge sensor (16). The contact pads (14) are shared between the electrostatic charge sensor (16) and drivers (18). The contact pads (14) are set to a high impedance state by reducing current leakage through the drivers (18). Compared to electrostatic charge sensor with low impedance contact pads, the electrostatic charge sensor disclosed herein has high sensitivity, and is able to detect weak electrostatic fields.