Analog multiplier

A method for multiplying a matrix with a vector in a compute-in-memory matrix multiplier, comprising:

• storing the matrix in an array, wherein the array comprises a plurality of sub arrays, each sub array having rows and groups of columns of storage cells, wherein the storing comprises storing, in each sub array, values of a sub matrix of the matrix in the storage cells, wherein each element of the matrix is stored in a row across a group of columns, each column of the group of columns associated with a bit value of an element of the sub matrix, wherein each sub array is associated with a scale;
• performing a first operation, comprising:
• for each sub array, obtaining a dot product for each bit value of each column with at least a portion of the vector;
• subsequent to performing the first operation, performing a second operation comprising any one of two options, wherein the two options are:
• for each group of columns for each sub array, obtaining a weighted sum of the group of columns according to the associated bit value for each column of the group of columns;
• and
• multiplying each sub array with the scale associated with the sub array and obtaining a sum of the columns of the scaled sub arrays corresponding to a column of the matrix;
• subsequent to performing the second operation, performing a third operation, wherein the third operation comprises performing the other one of the two options.