Capacitance Detection Circuit Layout for Smaller Touch ICs
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Solution Overview
Problem
The increasing trend of thinning touch panels in electrostatic capacitance type touch devices leads to higher production costs due to the increased area occupied by reference capacitors integrated on semiconductor chips, necessitating a reduction in chip area for capacitance detection circuits.
Innovation Solution
A capacitance detection circuit design that includes a sense pin connected to a sensor electrode, a reference capacitor, and multiple driving units and switches to apply high or low voltage to the capacitor terminals, allowing for reduced chip area by minimizing the number of reference capacitors and optimizing the layout of capacitive elements, including Metal-Insulator-Metal (MIM) capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple reference capacitors are integrated on a semiconductor chip to detect electrostatic capacitance, then the detection capability is improved, but the chip area increases and production costs rise
Solution Approach 1:
The patent combines multiple reference capacitors into a single integrated reference capacitor structure on the semiconductor chip. The circuit uses switching elements to connect this single reference capacitor to multiple sensor electrodes sequentially, eliminating the need for separate reference capacitors for each electrode and significantly reducing chip area while maintaining capacitance detection capability.
Solution Approach 2:
The single reference capacitor serves multiple functions by being sequentially connected to different sensor electrodes through switching elements. This universal reference capacitor performs capacitance measurement for multiple electrodes, replacing what would traditionally require multiple dedicated reference capacitors, thus reducing overall chip area while preserving measurement precision.
2Measurement precision
If multiple reference capacitors are integrated on a semiconductor chip, then capacitance measurement accuracy is maintained, but production costs increase
Solution Approach 1:
By merging multiple reference capacitors into a single integrated structure with switching elements, the patent reduces the total component count and circuit complexity. This simplification lowers manufacturing costs while the sequential switching mechanism maintains measurement accuracy by providing dedicated reference capacitance for each electrode measurement.
Solution Approach 2:
The circuit temporarily connects the reference capacitor to different sensor electrodes in sequence through switching elements, allowing the same reference capacitor to be recovered and reused for multiple measurements. This approach eliminates the need for permanent dedicated reference capacitors for each electrode, reducing production costs while maintaining 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 solution effectively reduces the chip area required for capacitance detection circuits, maintaining uniform circuit characteristics while integrating the circuit on a semiconductor chip, thus lowering production costs and improving efficiency.
Implementation Method 1
a reference capacitor Cr; a first driving unit 212 configured to apply a high voltage VH or a low voltage VL to the sense pin SNS; a second driving unit 214 configured to apply the high voltage VH or the low voltage VL to a first terminal e1 of the reference capacitor Cr; a third driving unit 216 configured to apply the high voltage VH or the low voltage VL to a second terminal e2 of the reference capacitor Cr
Data Source
AI summary
The present disclosure provides a capacitance detection circuit capable of reducing a chip area. The present disclosure relates to a capacitance detection circuit and an input device. A sense pin of the capacitance detection circuit is connected to a sensor electrode. A first driving unit applies a high voltage or a low voltage to the sense pin. A second driving unit applies the high voltage or the low voltage to a first terminal of a reference capacitor. A third driving unit applies the high voltage or the low voltage to a second terminal of the reference capacitor. A first switch is disposed between the sense pin and the first terminal of the reference capacitor. A second switch is disposed between an input of a post-stage circuit block and the first terminal of the reference capacitor.