Addition is a vital arithmetic operation and is the base of other arithmetic operations such as multiplication, subtraction and division. Adder is a digital circuit that does addition of binary numbers. The 1-bit full adder is the basic block of an arithmetic unit. In VLSI, there are many efficient techniques to design digital circuits. Some of the techniques are Pass Transistor logic (PTL), Complementary metal oxide semiconductor (CMOS) and Transmitter gate (TG). There are several adder designs implemented to reduce the power. However, each design undergoes from precise disadvantage. The adder design with good driving capability requires more power and the design with more delay which consumes less power. In this paper 8-bit Carry Increment Adder (CIA), Carry Bypass Adder (CBA), Carry Skip Adder (CSKA), Carry Look Ahead Adder (CLA), Kogge Stone Adder (KSA), Han Carlson Adder (HCA), and Brent Kung Adder (BKA) are implemented using Gate Diffusion Input (GDI) logic. These designs are simulated and implemented using Tanner tool. The result shows that CBA, CLA, and KSA designs using GDI logic are more efficient compared to CMOS logic in view of power consumption, delay, and area (transistors count) respectively

Addition is a vital arithmetic operation. It is the base of commonly used arithmetic operations such as division, subtraction, and multiplication. Adder is a digital circuit that accomplishes addition of numbers. The one bit full adder is the basic block of an arithmetic unit. There are several adder designs implemented so far to reduce the power. However, each design suffers from exact drawback. Reversible logic is the growing technology in the current era. The numbers of input and output lines in reversible logic are equal. In reversible logic the inputs are to be recovered from the outputs. Reversible logic gates are defined by the user. In this paper Carry Skip Adder (CSKA) is implemented in two different designs i.e. design-I and design-II. Design-I is implemented using Peres gates with irreversible (XOR, AND, OR) logic gates. Design-II is implemented using PERES, TOFFOLI, and FREDKIN reversible logic gates. Design-I and design-II designs are synthesized and simulated by Mentor Graphics tool. Design-II is more efficient in terms of transistor count and power consumption compared to DesignI.

The digital data can be easily modified and copied, so it is not secure, so owner authentication is required to prevent this unauthorised access of digital data. Image signature (water mark) is required to embed with digital data. The Discrete Wavelet Transform (DWT) supports image signature algorithms possess dual resolution attaining imperceptibility. The Singular Value Decomposition (SVD) supports to achieving the robustness in order to add the signature information to the singular values of the diagonal matrix.. In this work implementing dual image signature method using DWT and SVD in YCbCr colour space. The cover image is embedded with dual images to achieve better security from unauthorized persons. The proposed method improves the robustness and imperceptibility of the cover image.