1 GHz leading zero anticipator using independent sign-bit determination logic

Abstract

The architecture and design methodology of a leading zero anticipator (LZA) using built-in sign-bit determination logic are described. The LZA was implemented in the 1 GHz floating point unit using a 1.8 V, 0.12/0.15 (n/p)μm Leff. IBM CMOS technology. The design shows 730 ps of latency and operates at 1 GHz with 5 levels of delayed reset dynamic circuit logic. With the LZA the sign-bit is determined in 446 ps with an area overhead of 8%, whereas a conventional adder generates the sign-bit in 770 ps.