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بسم الله الرحمن الرحيم |
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Ripple-Carry Adders: Addition is the most frequent operation which can be used also for multiplication and division. Therefore, fast two-operand adder is very essential. Parallel Adder with 3 FAs:
The above adder is called a Ripple-Carry Adder which has the following characteristics: ¨ In a parallel arithmetic unit: * All 2n input bits are available at the same time * Carries propagate from the FA in position 0 (with inputs x0 and y0) to position i before that position produces correct sum and carry-out bits * Carries ripple should through all n FAs before we can claim that the sum outputs are correct and may be used in further calculations ¨ ci may change later on resulting in a change in the final sum, si ¨ Ripple effect can be observed at sum outputs of the Ripple Carry Adder until carry propagation is complete. ¨ In synchronous arithmetic units, the allowed time for adder's operation is worst-case delay which is nDFA . |
- Unconventional Number System - Additive & Non-additive Multiplier - Counters |
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