Multiplier circuit suitable for obtaining a negative product of a multiplier and a multiplicand

摘要

A &upbar& P generator receives the multiplier data Y and produces the &upbar& P on the basis of the data Y2i, Y2i+1, and Y2i+2 of three continuous bits of the multiplier data Y (in which, it is defined that Pi=Y2i+Y2i+1-2xY2i+2, Pi=Y2i+Y2i+1-2xY2i+2' and Y0=0, and i=0, 1, . . . , n/2-1, and Yj is the bit data of the jth bit of the multiplier Y). A partial-product generator receives the &upbar& P from the &upbar& P generator and a multiplicand X, and obtains the partial products XxPi of the multiplicand X and the Pi. A partial-product adding circuit weights 22i to the partial products XxPi derived by the partial-product generator, and adds the resultant data, thereby producing the negative product (-XxY) of the multiplicand X and multiplier Y.