An optimised twin precision multiplier for ASIC environment

Abstract

In this paper, we present the performance of twin precision technique in reduced computation modified booth (RCMB) multiplier to achieve double throughput, and an algorithm is proposed. Twin precision technique is the efficient way to obtain double throughput in the multipliers. We describe how to apply twin precision technique to RCMB multipliers. Implementation of twin precision in RCMB multiplier requires lesser changes to be made in partial product array for obtaining double throughput. Multiplexers usually do the signal selection for N and N/2 bit multiplication. In RCMB multiplier, [N/2] + 1 partial product are reduced to N/2 rows. Our idea of implementing twin precision technique to RCMB results in less utilisation of multiplexers of about [N/2] + 3 which gave a way for optimization in the twin precision (TP) multiplier. Thereby, we have achieved the drastic reduction in multiplexer utilisation of about 40% to 50% (for N = 8 to 128) compared to the existing twin precision modified booth multiplier. In our proposed optimised TP modified booth multiplier this reduction in multiplexers gave a way for overall reduction in area, power and delay. Lesser utilisation of multiplexer results in the area reduction of about 5% to 18%, delay of 5% to 20% and a considerable reduction in power of 8% to 32% were noticed in the proposed TP booth multiplier for N = 8 to 128. Our proposed optimised TP multiplier is implemented in FFT complex multiplication which is taken as an application case study and achieves better performance (area, delay and power) compare to prior TP multiplier. All our evaluation are made using cadence RTL compiler using TSMC 180 nm library.