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A Design of HighSpeed 42 Compressor for Fast Multiplier
Hiroshi MAKINO Hiroaki SUZUKI Hiroyuki MORINAKA Yasunobu NAKASE Hirofumi SHINOHARA Koichiro MASHIKO Tadashi SUMI Yasutaka HORIBA
Publication
IEICE TRANSACTIONS on Electronics
Vol.E79C
No.4
pp.538548 Publication Date: 1996/04/25 Online ISSN:
DOI: Print ISSN: 09168516 Type of Manuscript: Special Section PAPER (Special Issue on UltraHighSpeed LSIs) Category: Keyword: 42 compressor, multiplier, redundant binary, transmission gate, CMOS circuit,
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Summary:
This paper describes the design of a highspeed 42 compressor for fast multipliers. Through the survey of the six kinds of representative conventional 42 compressor (RBA 13 and NBA 13) in both the redundant binary (RB) and the normal binary (NB) scheme, we extracted two problems that degrades the operating speed. The first is the use of multiinput complex gates and the second is the existence of transmission gates (TG) at the input and/or output stages. To solve these problems, we propose highspeed 42 compressors using the RB scheme, which we call the highspeed redundant binary adders (HSRBAs). Six kinds of HSRBAs, HSRBA 16, were derived by making the Boolean equations suitable for highspeed CMOS circuits. Among them, HSRBA2, HSRBA4 and HSRBA6 have no multiinput complex gate and input/output TG, and perform at a delay time of 0.89 ns which is the fastest of all 42 compressors. We investigated the logical relation between HSRBAs and conventional 42 compressors by analyzing the Boolean equations for each circuit. This investigation shows that all the conventional redundant binary adders RBA13 have the same logic structures as HSRBA2. We also showed the conventional normal binary adders NBA13 have the same logic structures as HSRBA1, HSRBA3 and HSRBA5, respectively. This implies all 42 compressors can be derived from the same equation regardless of RB or NB. We applied the HSRBA2 to a 5454bit multiplier using 0.5µm CMOS technology. The multiplication time at the supply voltage of 3.3 V was 8.8 ns. This is the fastest 5454bit multiplier with 0.5µm CMOS so far, and 83% of the speed improvement is due to the high speed 42 compressor.


