Abstract
In the design of any ALU, shift registers are generally used to perform addition (for carry movement), multiplication and for any floating point arithmetic. The shift registers currently used are made up of flip-flops which require n clock pulses for n shifts which can increase the delay. So, the aim is to design a high speed shift register i.e., barrel shifter which needs a single clock pulse for n shifts. In this paper, three types of Barrel shifter circuits called left rotator, right rotator and bidirectional rotators are designed in Cadence Virtuoso tool for 180nm and 45nm technology using universal gates (conventional model) and transmission gates. Compared to conventional design, the circuits of barrel shifters with transmission gates in 45nm technology require less power and reduced transistor count.The designed barrel shifter circuits are showing improved performance than conventional models already presented in the literature.
Highlights
An ALU (Arithmetic Logic Unit) is one of the main components that perform arithmetic operations in the math processor using shift registers within the DSP chip
In order to improve the performance of the ALU, shift registers can be replaced by high speed barrel shifters in Arithmetic and logic units (ALU), RISC processors, Digital signal processors [1]
Various types of four bit barrel shifter circuits are implemented using 4X1 multiplexer and the performance is analysed on the basis of speed, consumption of power and the transistors required to implement in 180nm and 45nm technology.A shift register is designed using D flip-flop
Summary
An ALU (Arithmetic Logic Unit) is one of the main components that perform arithmetic operations in the math processor using shift registers within the DSP chip. In order to improve the performance of the ALU, shift registers can be replaced by high speed barrel shifters in Arithmetic and logic units (ALU), RISC processors, Digital signal processors [1]. Various types of four bit barrel shifter circuits are implemented using 4X1 multiplexer and the performance is analysed on the basis of speed, consumption of power and the transistors required to implement in 180nm and 45nm technology.A shift register is designed using D flip-flop. Its disadvantage is that it takes n clock pulses to shift n bits which intern increases delay and results in more power consumption This can be eliminated by using barrel shifter where it requires only one clock pulse to shift n bits for n bit register using a control word[6]. The empty space created in the low order region is filled with zeros
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