A 13.3ns double-precision floating-point ALU and multiplier

Abstract

One-bit pre-shifting before alignment shift, normalization with anticipated leading '1' bit and pre-rounding techniques have been developed for a floating-point arithmetic logic unit (ALU). In addition, carry select addition and pre-rounding techniques have been developed for a floating-point multiplier. A noise tolerant precharge (NTP) circuit was designed and applied to the ALU and multiplier. These techniques reduced the delay time of the critical path by 24%. Each unit was fabricated in 0.3 /spl mu/m 2.5 V four-layer-metal CMOS technology and achieved a two-cycle latency at 150 MHz.