Circuit and method for partial product bit shifting

There are many conventional multiplication circuits that perform squaring. Typically, these circuits include an array of partial product bit generators, each bit generator providing a bit of a partial product by comparing the appropriate bits of the multiplicand and multiplier. A circuit for shifting the number of partial product bits per column in an adder tree is provided. A partial product bit is generated having a weight 2that has a 1 value only if one input bit of weight 2has a 0 value while another input bit of weight 2has a 1 value. Another more significant partial product bit of weight 2receives the same input bits and has a 1 value only if both of the input bits have a 1 value. In this manner, the number of partial product bits in the column of weight 2is decreased by 1 while the number of bits is the column of weight 2is increased by 1. Therefore, if the column of weight 2had the greatest number of partial product bits of all columns, and if the column of weight 2had at least two fewer bits than the column of weight 2, the total maximum number of bits for all the columns is reduced by 1.