Technology In VLSI Technology

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Abstract— Advancement in the VLSI technology leads to the reduction in chip size and increase in chip density. As the chip density increases the overall power consumption and the complexity also increases. As the performance of any system is measured mainly on power consumption, it is recommended to use low power VLSI Design techniques. In this paper, we would discuss the GDI logic and its application in the modeling of adders for Vedic Multiplier design. Adders are of prime importance, the design of reliable and efficient adder for a VLSI based embedded application matters. This paper primarily deals with the design of Ripple Carry Adder, Kogge Stone Adder, and Brent Kung Adder using CMOS and GDI logic. Urdhava Triyagbhayam sutra is used…show more content…
II. GDI LOGIC Gate Diffusion Input (GDI) logic is a low power Very Large Scale Integrated (VLSI) design technique which was introduced as an alternative to CMOS logic design. This technique is a two transistor implementation of complex logic functions; Logic functions can be designed with fewer gates. GDI provides in cell swing restoration when operated in certain conditions and use of restoration buffers. Digital circuits designed using GDI logic will have less power consumption occupy a minimum area, gate count and delay in the circuit is reduced. Because of fewer gates, there is less design complexity.GDI cell is as shown in the below figure 2.1 GDI cell looks similar to the CMOS inverter but the major difference is that the GDI cell has one PMOS and NMOS transistors connected in cascade resulting in three input terminals N, P, G. where N is the input terminal of NMOS, P is input to the PMOS and G is connected to the common gate of NMOS and PMOS. These terminals could be given a supply VDD or Grounded or input signal depending on the circuit design. In conventional CMOS inverter circuit, the PMOS and NMOS diffusion inputs are always either VDD or Ground Figure -2.1 Basic logic functions of GDI cell are as shown in the table below. Using which basic logic gates can be designed and implemented for the design of higher digital circuits like half adders, full adder, Ripple Carry Adder, Black cell, propagation and
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