I. Introduction
The use of sensing in interfaces between electronic systems and users has become more prevalent. A touch sensitive device enables users to perform various functions by touching the touch sensor panel with their finger. A common use of touch sensing technology is capacitive sensing [1] –[8]. A touch sensitive device can detect the touching location of a user's finger only when the user's finger touches the sensor panel. As presented in previous research [9], some touch sensitive devices can also recognize a floating event. When an object is near but not touching the touch sensor panel, the touch sensitive device can process the floating event in a manner similar to that of a touch event. Because of the sensing mechanism and signal strength, traditional touch sensitive devices do not sense floating events easily. The other previous work [10] has already demonstrated a practical solution to this problem by forming a specific electric field. The electric field is complete when not interrupted by the entrance of an object; however, the electric field is disturbed and broken when an object enters it. The major methodology of the floating sensing is similar to traditional wireless communications. However, its drawback is its large power consumption and it would face some electromagnetic interference issue.