STMicroelectronics' new FingerTip touchscreen technology
Improved noise immunity

– STMicroelectronics ( www.st.com ), a world-leading integrated semiconductor company and the No. 1 provider of MEMS (Micro-Electro-Mechanical Systems) for consumer electronics and mobile devices, has announced a new touchscreen technology called FingerTip. By utilizing this technology, a single-chip solution is possible for use on capacitive touchscreens with a diameter of up to 10 inches with multi-touch capabilities.

ST's MEMS sensors and FingerTip technology utilize a similar architecture that connects sensor elements to high-performance capacitive sensing circuits. Leveraging its accumulated know-how in analog and analog/digital mixed-signal interface technologies, ST has developed an innovative analog front-end solution capable of detecting capacitance fluctuations at the attofarad (10⁻¹⁸F) level and improving system noise immunity.

Touchscreen applications are susceptible to noise interference from various sources, such as the display, system, human touch, and battery chargers. In particular, low-cost, faulty chargers can generate noise reaching tens of volts, which can affect the normal operation of fingers touching the screen. When this situation occurs, strong periodic noise reaching 100V (peak-to-peak) and having a frequency range of 1kHz to 1MHz is introduced into the analog front end of the touchscreen controller, which can cause finger touches to be misrecognized.

ST's new FingerTip capacitive sensing technology utilizes a powerful 32-bit DSP (digital signal processing) engine to eliminate such charger noise, achieving higher immunity to noise without compromising performance in terms of accuracy, frame rate, or power consumption. FingerTip technology is also designed to eliminate noise from displays and works with both 'in-cell' and 'on-cell' display technologies.

Benedetto Vigna, General Manager of MEMS, Sensors, and High-Performance Analog at STMicroelectronics, said, "Noise from battery chargers can be a particular issue for touchscreens and can result in a degraded user experience. By utilizing ST's excellent analog-capacitive interface IP developed for MEMS sensors, superior noise rejection performance can be achieved prior to digital filtering. By using this new FingerTip technology, faster response times, reduced power consumption, and superior noise rejection performance required for high-end mobile applications can be achieved."

ST is conducting joint evaluations with key customers who can leverage the benefits of FingerTip, such as handwriting capabilities using a small stylus, very fast response times, extremely low power consumption, excellent linearity and accuracy in noisy conditions, and a small package suitable for smartphones and 10-inch tablets, for new products based on this new technology.