3 bit counter

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Components: JK flip-flop, digital sources, labels.
Theory: Binary ripple counters output the binary number sequence. A three bit binary up counter sequences from 000 to 111 and repeats the sequence on reaching 111. A cascade of n flip-flops can be used to configure a counter up to a modulus of 2n. A cascade of 3 flip-flops can be used to configure a counter up to modulus 8. The 3 bit binary up counter is shown below. With the count enable high, which is the J and K inputs, the output of each flip-flop toggles for every 0 to 1 transition of its clock input or at every positive edge of its clock input. The clock inputs of JKFF1 and JKFF2 are connected to the Q’ of the previous flip-flop. These flip-flops change state on the 1 to 0 transition of the Q outputs which correspond to 0 to 1 transition of the Q’ inputs. These binary counters are called ripple counters because the ith flip-flop is toggled by a change in the (i-1)th flip-flop. The pulses to be counted ripple through the counter.

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Created on: 05 Mar 2013
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