Integrated Capacitance Model Circuit for Sensing Calibration
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Solution Overview
Problem
Capacitance-sensing systems face challenges in ensuring all channels observe the same capacitance during characterization and calibration, leading to uncontrolled variations and difficulty in achieving accurate measurement accuracy due to reliance on external components with poor tolerances and the need for additional components on char boards.
Innovation Solution
An integrated capacitance model circuit is introduced, which is programmable and configured to model the capacitance of an external sense array, allowing all sensing channels to see a known capacitance and enabling built-in-self-test functionality, eliminating the need for external components and ensuring tight matching between on-chip capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If external capacitors are used for characterization and calibration, then capacitance variations can be tested, but measurement accuracy deteriorates due to uncontrolled variations and poor tolerances
Solution Approach 1:
The patent extracts the capacitance modeling function from external components and implements it within the capacitance-sensing device itself through an integrated capacitance model circuit. This eliminates reliance on external capacitors with poor tolerances and uncontrolled variations, thereby improving measurement accuracy while maintaining the ability to test capacitance variations through programmable control
Solution Approach 2:
The patent introduces an integrated capacitance model circuit as an intermediary between the sensing channels and the external environment. This model circuit provides a controlled, known capacitance reference that mediates the measurement process, enabling accurate characterization and calibration without the uncertainties of external capacitors
2Ease of manufacture
If external components are added to char boards for testing, then capacitance characterization is enabled, but device complexity increases
Solution Approach 1:
The patent merges the capacitance modeling functionality with the capacitance-sensing device by integrating the model circuit on the same substrate. This combination eliminates the need for separate external capacitors and char board modifications, thereby reducing device complexity and testing setup complexity while maintaining full characterization capability
Solution Approach 2:
The integrated capacitance model circuit serves multiple functions: it provides known capacitance references for calibration, enables characterization of sensing channels, and supports testing of capacitance variations through programmable control. This multi-functionality replaces what previously required multiple external components and setup modifications
3Ease of operation
If external capacitors with poor tolerances are used, then capacitance testing is possible, but manufacturing cost increases due to additional components
Solution Approach 1:
The patent extracts the capacitance reference function from external capacitors and implements it internally through programmable circuitry. This eliminates the need to source, assemble, and manage external capacitors with poor tolerances, thereby reducing manufacturing cost while maintaining ease of operation for capacitance testing through software control
Data Source
AI summary
Apparatuses and methods of an integrated capacitance model circuit are described. A capacitance model circuit is disposed on a common carrier substrate of an integrated circuit (IC) having a capacitance-sensing device. The capacitance model circuit is configured to model a capacitance of an external sense array. The capacitance model circuit is programmable.