However, the conventional carry-select adder (CSL) is still area-consuming due to In this paper, an area efficient square root CSL scheme based on a new first. Speed, delay and area are the performance parameters for any adder. Speed can be achieved by means of Square Root Carry Select Adder (SQRT CSLA). general, the basic square root carry select adder has a dual ripple carry adder with multiplexer, the main disadvantage of regular square root carry select.


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Ripple carry adders exhibits the most compact design but the slowest in speed. Carry select adders act as a compromise between the two adders.

In square root carry select adder, a new concept of hybrid adders is presented to speed up addition process by Wang etal. Inlow power multipliers based on new hybrid full adders is presented.

In digital adders, the speed of addition is limited by the time square root carry select adder to propagate a carry through the adder. The sum for each bit position in an elementary adder is generated sequentially only after the previous bit position has been summed and a carry propagated into the next position.

The CSLA is used in many computational systems to alleviate the problem of carry propagation delay by independently generating multiple carries and then select a carry to generate the sum.

However, the CSLA is not area efficient because it uses multiple pairs of Ripple Carry Adders RCA to generate partial sum and carry by considering carry input then the final sum and carry are selected by the multiplexers mux.

The modified block diagram is also divided into various groups of variable sizes of bits with each group having the Brent kung adders, BEC and corresponding MUX.

Carry-select adder

As shown in the Fig. Based on the consideration of delay values, the arrival time of selection input C1 of 8: Thus, the sum1 square root carry select adder c1 output from mux are depending on mux and results computed by BK adder and BEC respectively.

The sum2 depends on c1 and mux. Thus, the delay of the remaining MUX depends on the arrival time of mux selection input and the mux delay.

The multiplexer 4 to 1 and 2 to 1 are used. The signals c1,c2,c3,bc1,bc2,bc3,rc1,rc2,rc3 are generated. The Square root carry select adder kung adder, Bec and multiplexer combination will give the carry select adder for selection of the inputs for carry input0.

In this way the number of logics are reduced which makes this design as efficient interms of delay and power.

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We will set this unit under test as the top module and check syntax in implementation. After checking the errors if any errors are present we will try to minimize the errors and correct them. Once we get the zero errors square root carry select adder implementation is carried out further simulation.

In simulation,we will simulate the behavioural model and it will give us the required output of addition for 64 bits.

Design of Modified Area Efficient Square Root Carry Select Adder (SQRT CSLA)

Once this delay is known we will note it down and go for the power analysis. The power analysis is done using power analyzer in which we get the report on amount of power consumption.


They give us the real time experience which lead us to the true working of the product design. The delay of this adder will be four full adder delays, plus three MUX delays.

Square root carry select adder

Variable-sized adder[ edit ] A bit carry-select adder with variable size can be similarly created. Here we show an adder with block square root carry select adder of This break-up is ideal when the full-adder delay is equal to the MUX delay, which is unlikely. The total delay is two full adder delays, and four mux delays.


We try to make the delay through the two carry chains and the delay of the previous stage carry equal. Conditional sum adder[ edit ] A conditional sum adder is a recursive structure based on the carry-select adder.


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