A reconfigurable logic circuit based on threshold elements with a controlled floating gate

This paper presents a reconfigurable logic circuit based on threshold elements consisting of floating-gate devices with a controlled floating gate. The aim of controlling a floating-gate voltage and charge is to increase the number of input variables that the threshold elements can handle. With more input variables, the threshold elements work more effectively. A circuit for threshold elements addressed here has a feedback loop with a switch that connects an output terminal of a CMOS inverter to its floating-input gate. Such a switch with leakage currents causes a problem that a floating gate is no longer insulated electrically. Also circuit techniques are introduced to compensate for weaknesses that originate in the problem. The reconfigurable circuit realizes five main functions: any symmetric function of seven input variables, any logic function of three input variables, partially symmetric functions, an 8-bit memory, and a wire function.