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Four-Input Carry Save Adder Tree

IP.com Disclosure Number: IPCOM000035752D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Weinberger, A: AUTHOR

Abstract

Fig. 1 shows a full adder implemented with DCS (Differential Current Switch) logic, using two types of primitive logic functions that DCS logic provides: Exclusive-OR and 2-way Select. (Image Omitted)

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Four-Input Carry Save Adder Tree

Fig. 1 shows a full adder implemented with DCS (Differential Current Switch) logic, using two types of primitive logic functions that DCS logic provides: Exclusive-OR and 2-way Select.

(Image Omitted)

In a carry save adder tree, a set of inputs can be reduced to 2 outputs by means of a tree of full adders. The last two reductions, from 4 inputs to 2 outputs, is done by means of 2 full adders in series using 6 gates in 4 gate levels, as shown in Fig. 2.

In Fig. 3, the 4-to-2 reduction is implemented in 3 gate levels using the same 6 gates, according to the equations.

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