Abstract: A coding method of a multi-level cell, applied to a programming operation of a multi-level memory cell. The multi-level memory cell can store n bits and has 2n levels with respect to 2n codes. Each code is constructed with n bits. In the coding method, a code to be stored is provided. According to a relationship between the code and level, the multi-level memory cell has a specified level for corresponding code to be stored. The relationship is a correspondence between the 2n codes and the 2n levels. Two codes corresponding to any neighboring two levels has only a one-bit difference.

Abstract: The present invention provides a protection circuit comprising one diode wherein the diode is formed by diffusing a heavily doped material of a first conductivity type into a first region of a second conductivity type. An integrated circuit, such as a memory array, is coupled to the diode. The other diode back-to-back is coupled to the diode wherein the other diode is formed by diffusing a heavily doped material of the second conductivity type into the first region and a second region of the first conductivity type. The two diodes in series are capable of discharging for the memory array during manufacturing process.