04/13/2023DEEPESH1

BANSAL COLLEGE OF ENGG. MANDIDEEP

SHIFTERS

PRESENTED BY: PRESENTED TO:

ATUL VERMA(EC25) MRS. RAVITESH MISHRA BHARTI RAJPUT(EC29)DEEPESH SHUKLA(EC32) A.P. BCE, MANDIDEEP PARUL CHOUDHARY(EC63)SANDESH GOHATIYA(EC88)

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PRESENTATION CONTENT

Introduction of shiftersTypes of shifters• Logical shifter• Arithmetic shifter• Barrel shifter• Funnel shifterTypes of funnel shifters

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INTRODUCTION OF SHIFTER

Shifters are important element in many microprocessor design for arithmetic shifting, logical shifting, and rotation (Barrel shifter) functions.

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TYPES OF SHIFTER

There are several commonly used shifters-•Logical shifter•Arithmetic shifter•Barrel shifter(rotator)•Funnel shifter

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LOGICAL SHIFTER

It shift the number to the left or right and fills empty spots with 0’s.

Example-

Logic Shift Right 2 110110 → _ _1101 → 001101

Example-

Logic Shift Left 2 110110 → 0110_ _ → 011000

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ARITHMETIC SHIFTER

Same as logical shifter, but on right shift fills the most significant bits with copies of the sign bit (to properly sign, extend 2’s complement numbers when using right shift by k for division by 2^k). Example- Arithmetic Shift Right 2 110110 → _ _1101 → 111101 For Left shift, same as Logic Shifter.

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BARREL SHIFTER

•Barrel shifter is a very important part of a combinational logic block.

•It have the ability to shift data work in a single operation over standard shift left or right registers that utilize more than one clock cycle.

•Rotates numbers in a cycle such that empty spots are filled with bits shifted off the other end.

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Example- Barrel Shift Right 2

110110 → _ _1101 → 101101Example- Barrel Shift Left 2

110110 → 0110_ _ → 011011

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FUNNEL SHIFTER

The funnel shifter perform all there such operations.

•Logic Shift Right• Logic Shift Left•Arithmetic Shift Right• Arithmetic Shift Left• Barrel Shift Right• Barrel Shift Left.

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FUNCTION OF DESIGN

B is filled with bits based on original number is Cwhat kind of shifter we want. Output is Y.

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TABLE – FUNNEL SHIFTER

Table lists what inputs should be applied to perform a left or right shift of an n-bit word A by k bits.Generating the offset for left shifts requires a 2’s complement subtraction.

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TABLE- FUNNEL SHIFTER OPERATION

What kind of shifter is determined by input Z.

Right or left is determined by offset.

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TYPES OF FUNNEL SHITER

There are two different types of funnel shifters.

•Array funnel shifter•Multilevel funnel shifter

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ARRAY FUNNEL SHIFTER

The simplest funnel shifter design consist o an array of n- input multiplexers accepting 1 of n-hot select signals (one multiplexer for each output bit ). Such an array shifter is shown in figure using n- mos pass transistor for a 4 bit shifter. The shift amount is conditionally inverted and allocated into select signals that are fed vertically across the array. The outputs are taken horizontally. Each row of transistors attached to an output forms one of the multiplexers.

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Inverters and decoders

Y3

Y2

Y1

Y0

Left

K[1:0]

S3 S2 S1 S0

Z6

Z5

Z4

Z3 Z2 Z1 Z0ARRAY FUNNEL SHIFTER

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The array funnel shifter works reasonably well for medium sized shifters in transistor level design, but has high parasitic capacitance in larger shifters and is not amenable to standard cell designs.

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MULTILEVEL FUNNEL SHIFTER

K1 K0 determines offset

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Fig. shows a 4 bit shifter based on multiple levels of smaller multiplexers (which of course, can be transmission gates). In general, the first level shift +n/2 the second by n/4, and so fourth until the find level shift with such a structure, no decoder is necessary. The XOR gates on the control inputs conditionally invert the shifts.

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THANKYOU

04/13/2023BHARTI