Electronics
In electronics, digital circuits and digital electronics, the propagation delay, or gate delay, is the length of time which starts when the input to a logic gate becomes stable and valid, to the time that the output of that logic gate is stable and valid. Often this refers to the time required for the output to reach from 10% to 90% of its final output level when the input changes. Reducing gate delays in digital circuits allows them to process data at a faster rate and improve overall performance.
The difference in propagation delays of logic elements is the major contributor to glitches in asynchronous circuits as a result of race conditions.
The principle of logical effort utilizes propagation delays to compare designs implementing the same logical statement.
Propagation delay increases with operating temperature, marginal supply voltage as well as an increased output load capacitance. The latter is the largest contributor to the increase of propagation delay. If the output of a logic gate is connected to a long trace or used to drive many other gates (high fanout) the propagation delay increases substantially.
Wires have an approximate propagation delay of 1 ns for every 6 inches (15 cm) of length. Logic gates can have propagation delays ranging from more than 10 ns down to the picosecond range, depending on the technology being used.
Read more about this topic: Propagation Delay
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“We live in a highly industrialized society and every member of the Black nation must be as academically and technologically developed as possible. To wage a revolution, we need competent teachers, doctors, nurses, electronics experts, chemists, biologists, physicists, political scientists, and so on and so forth. Black women sitting at home reading bedtime stories to their children are just not going to make it.”
—Frances Beale, African American feminist and civil rights activist. The Black Woman, ch. 14 (1970)