Optimal detection voltage obtaining method, reading control method and apparatus of memory

A read control apparatus of a memory, comprising:

• a hard decoding block for performing hard decision decoding of LDPC under the optimal detection voltage to obtain first data;
• a soft decoding block for performing soft decision decoding on the first data to obtain second data;
• an LDPC decoder block for performing LDPC decoding on the second data to obtain final output data,
• wherein an optimal detection voltage obtaining method comprises following steps:
• performing a plurality of read operations at a plurality of detection voltages to obtain a plurality of first difference values and a plurality of second difference values, wherein the second difference value characterizes a difference value of two detection voltages which are adjacent in numerical value, and the first difference value characterizes a difference between numbers of memory cells whose threshold voltages respectively equal to the two detection voltages used by the second difference value;
• dividing the first difference by the second difference to obtain a plurality of tangent approximations;
• selecting a first tangent approximation and a second tangent approximation from the plurality of tangent approximations, the first tangent approximation is a positive number and the second tangent approximation is a negative number;
• calculating an optimal detection voltage according to the first tangent approximation, the second tangent approximation, a first detection voltage corresponding to the first tangent approximation and a second detection voltage corresponding to the second tangent approximation.