Hubert Halbritter

High-Speed LED Driver for ns-Pulse Switching of High-Current LEDs

This letter analyzes the intrinsic optical switching response of state-of-the-art high power, multiquantum wells, thin-film, and surface-textured infrared light emitting diodes (LEDs). For the switching time response of such devices, the theoretical basics are presented and their predictions are experimentally verified. In the second part of this letter, a novel, fast switching LED driving circuit is presented which enables nanosecond-pulse operation. The circuit reduces significantly the optical rise and fall time of LEDs from 10/15 ns, respectively, down to 2.6 ns at 2-A pulse current without compromising the peak output power.

Why infrared is catching the eye in smartphone security

The uniqueness of people is the basis for biometric identification methods. Fingerprint scanners and iris or facial recognition have long been established as access controls for sensitive areas. Nowadays, though, smartphones and tablets also need particular protection, as their users increasingly carry out sensitive activities such as banking transactions, purchasing or their professional communications. We are therefore seeing these biometric methods being deployed across the market to help people keep their smartphones secure.