scholarly journals SOPHISTICATED DESIGN OF LOW POWER HIGH SPEED FULL ADDER BY USING SR-CPL AND TRANSMISSION GATE LOGIC

Author(s):  
Sai Venkatramana Prasada G.S ◽  
G. Seshikala ◽  
S. Niranjana

Background: This paper presents the comparative study of power dissipation, delay and power delay product (PDP) of different full adders and multiplier designs. Methods: Full adder is the fundamental operation for any processors, DSP architectures and VLSI systems. Here ten different full adder structures were analyzed for their best performance using a Mentor Graphics tool with 180nm technology. Results: From the analysis result high performance full adder is extracted for further higher level designs. 8T full adder exhibits high speed, low power delay and low power delay product and hence it is considered to construct four different multiplier designs, such as Array multiplier, Baugh Wooley multiplier, Braun multiplier and Wallace Tree multiplier. These different structures of multipliers were designed using 8T full adder and simulated using Mentor Graphics tool in a constant W/L aspect ratio. Conclusion: From the analysis, it is concluded that Wallace Tree multiplier is the high speed multiplier but dissipates comparatively high power. Baugh Wooley multiplier dissipates less power but exhibits more time delay and low PDP.


2012 ◽  
Vol 9 (24) ◽  
pp. 1900-1905
Author(s):  
Kamran Delfan Hemmati ◽  
Mojtaba Behzad Fallahpour ◽  
Abbas Golmakani ◽  
Kamyar Delfan Hemmati

Author(s):  
M. Naga Gowtham Et.al

In this paper, a hybrid 1-bit adder and 1-bit Subtractor designs are implemented. The hybrid adder circuit is constructed using CMOS (complementary metal oxide semiconductor) logic along with pass transistor logic. The design can be extended 16 and 32 bits lately. The proposed full adder circuit is compared with the existing conventional adders in terms of power, delay and area in order to obtain a better circuit that serves the present day needs of people. The existing 1-bit hybrid adder uses EXNOR logic combined with the transmission gate logic. For a supply voltage of 1.8V the average power consumption (4.1563 µW) which is extremely low with moderately low delay (224 ps) resulting because of the deliberate incorporation of very weak CMOS inverters coupled with strong transmission gates. At 1.2V supply the power and delay were recorded to be 1.17664 µW and 91.3 ps. The design was implemented using 1-bit which can also be extended into a 32-bit design later. The designed implementation offers a better performance in terms of power and speed compared to the existing full adder design styles. The circuits were implemented in DSCH2 and Microwind tools respectively. The parameters such as power, delay, layout area and speed of the proposed circuit design is compared with pass transistor logic, adiabatic logic, transmission gate adder and so on. The circuit is also designed with a decrease in transistors in order to get the better results. Full Subtractor, a combinational digital circuit which performs 1-bit subtraction with borrow in is designed as a part of this project. The main aim behind this part of the project is to design a 1-bit full Subtractor using CMOS technology with reduced number of transistors and hence the efficiency in terms of area, power and speed have been calculated is designed using 8,10,15and 16 transistors. The parameters were calculated in each case and the results have been tabulated.


VLSI technology become one of the most significant and demandable because of the characteristics like device portability, device size, large amount of features, expenditure, consistency, rapidity and many others. Multipliers and Adders place an important role in various digital systems such as computers, process controllers and signal processors in order to achieve high speed and low power. Two input XOR/XNOR gate and 2:1 multiplexer modules are used to design the Hybrid Full adders. The XOR/XNOR gate is the key punter of power included in the Full adder cell. However this circuit increases the delay, area and critical path delay. Hence, the optimum design of the XOR/XNOR is required to reduce the power consumption of the Full adder Cell. So a 6 New Hybrid Full adder circuits are proposed based on the Novel Full-Swing XOR/XNOR gates and a New Gate Diffusion Input (GDI) design of Full adder with high-swing outputs. The speed, power consumption, power delay product and driving capability are the merits of the each proposed circuits. This circuit simulation was carried used cadence virtuoso EDA tool. The simulation results based on the 90nm CMOS process technology model.


Author(s):  
M. Naga Gowtham, P.S Hari Krishna Reddy, K Jeevitha, K Hari Kishore, E Raghuveera, Shaik Razia

In this paper, a hybrid 1-bit adder and 1-bit Subtractor designs are implemented. The hybrid adder circuit is constructed using CMOS (complementary metal oxide semiconductor) logic along with pass transistor logic. The design can be extended 16 and 32 bits lately. The proposed full adder circuit is compared with the existing conventional adders in terms of power, delay and area in order to obtain a better circuit that serves the present day needs of people. The existing 1-bit hybrid adder uses EXNOR logic combined with the transmission gate logic. For a supply voltage of 1.8V the average power consumption (4.1563 µW) which is extremely low with moderately low delay (224 ps) resulting because of the deliberate incorporation of very weak CMOS inverters coupled with strong transmission gates. At 1.2V supply the power and delay were recorded to be 1.17664 µW and 91.3 ps. The design was implemented using 1-bit which can also be extended into a 32-bit design later. The designed implementation offers a better performance in terms of power and speed compared to the existing full adder design styles. The circuits were implemented in DSCH2 and Microwind tools respectively. The parameters such as power, delay, layout area and speed of the proposed circuit design is compared with pass transistor logic, adiabatic logic, transmission gate adder and so on. The circuit is also designed with a decrease in transistors in order to get the better results. Full Subtractor, a combinational digital circuit which performs 1-bit subtraction with borrow in is designed as a part of this project. The main aim behind this part of the project is to design a 1-bit full Subtractor using CMOS technology with reduced number of transistors and hence the efficiency in terms of area, power and speed have been calculated is designed using 8,10,15and 16 transistors. The parameters were calculated in each case and the results have been tabulated.


Author(s):  
Nakul C. Kubsad

Abstract: Full adder circuit is one among the fundamental and necessary digital part. The full adder is be a part of microprocessors, digital signal processors etc. It's needed for the arithmetic and logical operations. Full adder design enhancements are necessary for recent advancement. The requirement of an adder cell is to provide high speed, consume low power and provide high voltage swing. This paper analyses and compares 3 adders with completely different logic designs (Conventional, transmission gate & pseudo NMOS) for transistor count, power dissipation and delay. The simulation is performed in Cadence virtuoso tool with accessible GPDK – 180nm kit. Transmission gate full adder has sheer advantage of high speed, fewer space and also it shows higher performance in terms of delay. Keywords: Delay, power dissipation, voltage, transistor sizing.


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