What is the standard TTL noise margin ?
What is the standard TTL noise margin ? Correct Answer 0.4 V
Noise Margin:
- In a digital circuit, the Noise Margin is the amount by which the signal exceeds the threshold for a proper ‘0’ or ‘1’.
- For Ex: a Digital circuit might be designed to swing between 0 and 1.2 Volts, with anything below 0.2 V considered as a ‘0’ and anything above 1 Volt is considered a ‘1’. Then the noise margin for a ‘0’ would be the amount that a signal is below 0.2 Volts, and a noise margin for 1 would be the amount by which a signal exceeds 1 Volt.
- In this case noise margins are measured as an absolute voltage, not as a ratio.
- This is schematically explained with the help of the following diagram:
This is schematically explained with the help of the following diagram:
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A comparison of the given logic families is as shown:
|
|
TTL |
ECL |
CMOS |
|
Fan-In |
12-14 |
> 10 |
> 10 |
|
Fan-Out |
10 |
25 |
50 |
|
Power Dissipation (mW) |
10 |
175 |
0.001 |
|
Noise Margin |
0.4 V |
0.16 V (lowest) |
1.5 V (Highest) |
|
Propagation Delay |
10 |
< 3 (lowest) |
15 (Highest) |
|
Noise Immunity |
Very good |
Good |
excellent |
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Feb 20, 2025