I need to design a digital circuit that detects when a sequence of 0s does NOT contain a 1 followed by 1 (or more).


00000000010001000000000 Output: 1

00000011000000010000000 Output: 0

I know how to design a sequence detector, but this case is a little bit different since it needs to check the whole sequence before giving an output.

Thank you.


1 Answer 1


Either I am missing something, or this is pretty straightforward. Look at the diagram below. when the second 1 gets clocked in, your output switch to 0, and stays 0 until you reset the circuit for the next sequence. If no double zero appear in the stream, output stays 1.


simulate this circuit – Schematic created using CircuitLab

  • \$\begingroup\$ Not missing anything, but you are assuming the data stream is synchronous and has an available clock. \$\endgroup\$
    – Trevor_G
    Oct 17, 2017 at 1:20
  • \$\begingroup\$ True, unless angelustt chimes in, we won't know if those assumptions are valid. \$\endgroup\$
    – MAB
    Oct 18, 2017 at 0:40

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