Resistive Sensor Array Feedback Circuit for Switch Resistance Compensation
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Solution Overview
Problem
Existing passive sensor arrays face challenges in accurately reading large-area resistive sensor arrays due to cross-talk issues caused by finite resistance in column and row switches, which are not adequately compensated by current methods, leading to measurement inaccuracies and increased complexity and cost.
Innovation Solution
The proposed solution involves a compensated passive array with voltage feedback circuitry that includes dummy switches and compensation circuits to systematically match voltage level shifts at sensor array connections, reducing cross-talk by compensating for switch resistances, thereby improving measurement accuracy and simplifying sensor selection circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage feedback circuitry is used to read large-area resistive sensor arrays, then measurement accuracy is improved, but cross-talk errors from finite switch resistance are not adequately compensated
Solution Approach 1:
The patent implements a voltage feedback circuit that applies a feedback voltage to unselected columns equal to the voltage dropped across the selected resistive element. This feedback mechanism actively compensates for voltage drops caused by finite switch resistance, preventing cross-talk errors and improving measurement accuracy in large-area sensor arrays.
Solution Approach 2:
The patent introduces a feedback voltage as an intermediary signal that mediates between the selected sensor element and the unselected columns. This feedback voltage acts as a compensating signal that counteracts the harmful voltage drops caused by switch resistance, effectively eliminating cross-talk without requiring additional complex circuitry.
2Device complexity
If passive sensor arrays are used to reduce complexity, then device complexity is reduced, but switch resistance causes measurement errors
Solution Approach 1:
The patent maintains the simplicity of passive sensor arrays by implementing a voltage feedback circuit that compensates for switch resistance effects. The feedback mechanism provides the necessary correction without requiring active elements at each sensor location, thus preserving the low complexity advantage while improving measurement accuracy.
3Ease of manufacture
If finite resistance switches are used in column and row selection, then ease of manufacture is improved, but cross-talk and measurement inaccuracies increase
Solution Approach 1:
The patent accepts the use of finite resistance switches for ease of manufacture and compensates for their inherent voltage drops through a voltage feedback circuit. The feedback voltage is dynamically adjusted to match the voltage dropped across the selected element, thereby eliminating cross-talk errors despite the finite switch resistance.
Data Source
AI summary
An apparatus comprising: a passive array (202) of resistive elements (250); a row selector switch (204) and a column selector switch (206) configured to respectively connect a particular row and a particular column of resistive elements to ground; and a feedback column selector switch (208) configured to connect all columns of resistive elements to a voltage source, except for the particular column connected to ground by the column selector switch; the voltage source configured to apply a voltage to the columns of resistive elements, the voltage matching a voltage dropped over the resistive element connected in circuit by the row and column selector switches; and further comprising: a row selector switch compensation circuit (220), a column selector switch compensation circuit (240) and/or a feedback column selector switch compensation circuit (260) each configured to apply a voltage across a corresponding dummy element equal and opposite to a voltage dropped over the corresponding selector switch.