Buffered Differential Circuit for Touch Panel Noise Cancellation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Touch panels are affected by common mode noise, which reduces the accuracy of determining touch locations due to interference with receiving electrodes, especially when the Signal-to-Noise Ratio (SNR) is low.
Innovation Solution
A differential circuit with a middle electrode directly adjacent to first and second electrodes, coupled with amplifiers and buffers to block current diversion, utilizing high input impedance buffers between middle electrodes and amplifiers to prevent current flow and enhance signal accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If receiving electrodes are used in touch panels, then touch sensing capability is enabled, but common mode noise interferes with the electrodes reducing measurement precision
Solution Approach 1:
A buffer circuit is introduced as an intermediary component between the middle electrode and the amplifiers. This buffer acts as a mediator that blocks current diversion to the middle electrode, preventing common mode noise from affecting the differential signal measurement while maintaining the touch sensing functionality.
Solution Approach 2:
The input impedance of the buffer is designed to be significantly higher than the impedance of the middle electrode (e.g., 100 times higher). This parameter change ensures that current flow through the middle electrode is minimized, effectively blocking common mode noise propagation while preserving the differential signal integrity.
2Measurement precision
If middle electrodes are coupled directly to amplifiers, then circuit complexity is reduced, but current diversion occurs reducing signal accuracy
Solution Approach 1:
The buffer serves as an intermediary component that is strategically placed only at middle electrodes where current diversion would occur. This targeted approach blocks harmful current paths while maintaining direct amplifier coupling at boundary electrodes, achieving signal accuracy without excessive complexity.
Solution Approach 2:
Buffers are applied selectively only to middle electrodes rather than all electrodes. This local application strategy addresses the specific problem of current diversion at middle electrodes while avoiding unnecessary complexity in the overall circuit design.
Data Source
AI summary
A differential circuit is provided. The differential circuit comprises a plurality of electrodes comprising at least a middle electrode, wherein the middle electrode is directly adjacent to a first electrode and a second electrode of the plurality of electrodes; a plurality of amplifiers, coupled to the plurality of electrodes; and at least a buffer, coupled between the middle electrode and at least one amplifier of the plurality of amplifiers.