Design and Analysis of Hybrid Tree Multipliers for Reduction of Partial Products

This paper confers one of the three phases of tree multipliers, i.e. the Partial Product reduction phase. In this paper four types of hybrid tree multipliers are studied and proposed using parallel counters (full adders and half adders) for reduction of Partial Products in multiplication operation. After ANDing the bits of multiplier and multiplicand, the Partial Products are arranged into two groups for reduction, each group uses a different technique for reduction of Partial Products, resulting in a fewer gates than the parent tree reduction techniques. The results of the proposed tree reduction techniques are then tabulated and compared with the parent tree multipliers. The performance comparison is done in terms of number of gate counts of half adder and full adders used in the Partial Product reduction phase. Four types of hybrid tree multipliers are presented using CSA (Carry Save Adder) Array multiplier, Wallace Tree multiplier, Modified Wallace Tree multiplier and Dadda Tree Multiplier. The results show significant reduction in number of full adders and half adders with the slight overhead of increased final addition stage of the hybrid multiplier. The proposed multipliers can prove to be the better choice for digital signal processing designs, image processing designs and processor architecture.