Explain glitch problem of ripple counter along with waveform.

Mumbai University > ELECTRO > Sem 3 > Digital Circuits and Designs

Marks: 5M

Year: May 2015

1 Answer
  • Glitch is a short duration pulse or spike that appears in the outputs of a ripple counter with number<$2_n$.

  • Consider the waveform of a MOD-3 ripple counter shown below. But in practice, at the third falling clock edge, $Q_B$ and $Q_A$ become 11 causing a pulse.

  • Hence output of reset logic goes low but after a short duration of time. Here 11 is an unwanted state. In the output waveform of $Q_A$, this short pulse is called a 'Glitch'.

  • The state diagram of glitch is shown below. We can see that the state machine temporarily goes into unwanted state 11 which causes glitching

  • The waveform of this situation is shown below.

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