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Aggressively Combat Noise in Capacitive Touch Applications | Cypress Semiconductor

Aggressively Combat Noise in Capacitive Touch Applications

Last Updated: 
Oct 08, 2013

Author: Jeff Erickson

A touchscreen device can be subject to many different noise sources, both internal and external, in a given day.  Charger and display noise are two of the most common and problematic noise sources today. As devices get thinner and noisier chargers enter the market, these challenges will only become tougher to manage. Additionally, many other everyday items can generate noise that causes interference, including radio signals, AC mains, and even fluorescent light ballasts. In the presence of noise, the positions reported by low-performance capacitive touch systems will be distorted impacting accuracy and reliability.

Today’s touchscreen controllers employ a wide variety of techniques both to increase SNR and to filter out bad data from noise: high-voltage Tx generated on-chip, specialized hardware acceleration, high-frequency Tx, adaptive frequency hopping, and saturation prevention techniques. However, touch technology continues to advance in how the touch controller utilizes these features, dynamically adapts to the noise present in the system, and accurately track touches despite changing environmental conditions.

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