Touch Sensing Circuit DC Voltage Compensation
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Solution Overview
Problem
Conventional touch sensing circuits have complex structures and high manufacturing costs due to the need for large compensation capacitors and high-bit multipliers for signal demodulation, which compromises circuit performance.
Innovation Solution
A touch sensing circuit with operational amplifier circuits and demodulating circuits that use direct-current voltage compensation and demodulating signals with flat waveforms to simplify the circuit structure and enhance performance, eliminating the need for compensation capacitors and using low-bit multipliers for demodulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If compensation capacitors are used to compensate touch sensing signals, then signal compensation is achieved, but circuit area increases and manufacturing costs increase
Solution Approach 1:
The patent extracts and removes the compensation capacitor from the circuit by using direct-current voltage compensation instead. The operational amplifier circuit directly compensates the touch sensing signal through voltage adjustment, eliminating the need for separate compensation capacitors and reducing circuit area.
Solution Approach 2:
The patent replaces the physical capacitor-based compensation mechanism with an electrical voltage-based compensation mechanism. Instead of using capacitive elements to store and release charge for compensation, the system uses direct-current voltage control through operational amplifiers to achieve signal compensation, thereby reducing hardware complexity and area.
2Measurement precision
If high-bit multipliers are used for signal demodulation, then demodulation accuracy is improved, but circuit complexity increases
Solution Approach 1:
The patent changes the parameter of the demodulating signal from a traditional sine wave to a square wave with flat waveform regions. This parameter change allows the use of low-bit multipliers instead of high-bit multipliers, as the square wave's discrete levels simplify the multiplication operation while maintaining adequate demodulation accuracy for touch sensing applications.
Solution Approach 2:
The patent uses low-bit multipliers instead of high-bit multipliers, accepting a slight reduction in precision in exchange for significantly reduced circuit complexity and manufacturing cost. The low-bit multipliers are simpler, cheaper components that suffice for the specific requirements of touch panel sensing.
3Ease of operation
If sine wave signals are used for demodulation, then signal processing is achieved, but high-bit multipliers are required increasing circuit complexity
Solution Approach 1:
The patent changes the waveform parameter from sine wave to square wave. The square wave demodulating signal has flat regions that simplify the multiplication operation, allowing the use of low-bit multipliers. This parameter change maintains signal processing capability while dramatically reducing circuit complexity.
Data Source
AI summary
A touch sensing circuit including a plurality of touch sensing channels is provided. Each of the touch sensing channels includes at least one operational amplifier circuit and a demodulating circuit. The operational amplifier circuit is configured to receive a touch sensing signal, and amplify the touch sensing signal. The operational amplifier circuit includes an operational amplifier. The operational amplifier has an inverting end, and the inverting end is coupled to a direct-current voltage. The demodulating circuit is coupled to the operational amplifier circuit. The demodulating circuit is configured to demodulate the amplified touch sensing signal by mixing the amplified touch sensing signal with a demodulating signal. In addition, a signal demodulating method is also provided.