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The parallel adder which we use in the digital circuits ,the carry output of each full adder stage is connected to the carry input of the next higher order stage.therefore,the sum and carry outputs of any stage cannot be produced until the input carry occurs;
This leads to a time delay in the addition process.This delay is known as carry propagation delay.
to the second question the propagation delay can be avoided in the binary parallel adder with the help of look ahead carry generator
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Wiki User
∙ 14y ago
Wiki User
∙ 14y agoPropagation delay can be avoided in a parallel adder by using look-ahead carry logic, so that the state of each bit is not waiting on the prior bit's value, i.e. the adder is not operating in ripple-carry mode.
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What are the disadvantages of ripple carry adder?
time delay
What are the characteristics of Diode transistor logic?
relatively large propagation delay.
What are the major components of a serial full adder circuit?
Two half adders, an OR gate, and a delay.
What is propagation delay in flip flops?
Propagation Delay In digital logic, every gate has got some finite amount of delay because of which the change in the output is not instantaneous to the change in the input. In simple terms, the times it takes for an input to appear at the output is called the propagation delay. In Figure 6, tPHL, describes the time it takes for an input to cause the output to change from logic-level-high to logic-level-low. Similarly, tPLH, refers to the delay associated when an input change causes the output to change from logic-level-low to logic-level-high. The overall delay is average of these two delays.
What is the main criterion for the design of digital circuits?
The main criterion for the design of digital circuits is to simplify your circuit so you don't get to use so many circuit elements there by improving upon the propagation delay of the circuit in effect.
Why do you use look ahead carry adder?
You use a look ahead carry adder to reduce the propagation delay effects caused by the ripple carry that would otherwise be used. With ripple carry, each stage is dependent on the preceding stage, and this is cumulative. With look ahead carry, the carries are computed in parallel, speeding up the overall process.
Advantages of carry look ahead adder?
You use a look ahead carry adder to reduce the propagation delay effects caused by the ripple carry that would otherwise be used. With ripple carry, each stage is dependent on the preceding stage, and this is cumulative. With look ahead carry, the carries are computed in parallel, speeding up the overall process.
What is another name for propagation delay?
Another name for propagation delay is latency.
What best defines propagation delay?
Propagation delay is the time it takes for electronic devices to switch from one logic state to another.
What are the disadvantages of ripple carry adder?
time delay
What are the 4 main types of delays occured in packet switching?
Processing delay Queuing delay Transmission delay Propagation delay
Which has a shorter propagation delay TTL or CMOS?
TTL
What is value of propagation delay of TTL logic?
it is in micro seconds
What is the condition for minimum size of the token ring?
propagation delay in the ring/transmission delay of the packet<1
How does a half adder work?
A full adder has three inputs - A, B, and CarryIn from the prior stage. It generates a Result and a Carryout with the truth table... ABC-RC 000-00 001-10 010-10 011-01 100-10 101-01 110-01 111-11 The adder can be a ripple adder, in which the propogation delay depends on the carry "rippling" through the logic, or it can be a look-ahead-carry type, which has constant propagation delay time, at the expense of more logic.
What are the characteristics of Diode transistor logic?
relatively large propagation delay.
Explain how propagation delay affects the speed of modern PCs?
A: I wouldn't call propagation delay that applies to other media. for a PC delay are parasitic in nature mostly layout. But the real and actual delay is inherited from the I/O which is the soul of PC speed. No matter how fast a PC is internally it must service those interrupts and that is really the delay actually
