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What is propagation delay and at what point on the waveform it is measured?
Propagation delay is equal to d / s where d is the distance and s is the wave propagation speed. In wireless communication, s=c, i.e. the speed of light. In copper wire, the speed s generally ranges from . 59c to .
What is meant by the propagation delay time of a waveform?
Propagation delay is defined as the flight time of packets over the transmission link and is limited by the speed of light. For example, if the source and destination are in the same building at the distance of 200 m, the propagation delay will be ∼ 1 μsec.
What is the relationship between propagation speed and propagation time?
Propagation delay The ratio of actual propagation speed to the speed of light is also called the velocity factor of the medium. The propagation delay of a physical link can be calculated by dividing the distance (the length of the medium) in meter by its propagation speed in m/s.
What is propagation delay in flip flops?
The propagation delay of the flip flops means a small delay occurs between the clock edge and the flip flop output, Q, becoming valid. This is the called the propagation delay of the flip flop and is denoted TFF in the diagram below.
What is propagation time?
In digital circuits, propagation time is the delay of the basic inverter of a given family. Thus, it measures the speed at which such family can operate.
Why is propagation delay measured at 50% of the input and output?
To explain this, consider a simple example of a CMOS inverter below with a capacitive load at the output, when you apply L->H transition at input the H->L transition at the output is not instantaneous rather takes some time due to the capacitive charging time factor.
How is the propagation delay of a CMOS inverter calculated?
Propagation Delay of CMOS inverter The propagation delay of a logic gate e.g. inverter is the difference in time (calculated at 50% of input-output transition), when output switches, after application of input. In the above figure, there are 4 timing parameters.
Why is propagation delay important in Schmitt trigger?
The propagation delay is still one value for one L→H→L input cycle. It becomes important if you only ever match on one transition type, which is often the reason why you have a Schmitt trigger in a circuit. Take care. If you had open collector or open drain outputs, you have to put more thought into the drive strength on the L→H output transition.
Propagation delay of electrical signals is proportional to a RC time delay constant, where R is the resistance of the conductor allowing signal propagation and C is the parasitic capacitance that surrounds the conductor. As the minimum feature sizes decrease, the RC time delay naturally increases.