Digital Electronics - Flip-Flops - Discussion

Discussion Forum : Flip-Flops - General Questions (Q.No. 19)
19.

Four positive edge-triggered D flip-flops are used to store a 4-bit binary number as shown below. Determine if the circuit is functioning properly, and if not, what might be wrong.

The circuit is functioning properly.
Q2 is incorrect; the flip-flop is probably bad.
The input to flip-flop 3 (D2) is probably wrong; check the source of D2.
A bad connection probably exists between FF-3 and FF-4, causing FF-3 not to reset.
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
12 comments Page 1 of 2.

Neha agrawal said:   1 decade ago
As there are two enable signals in each f/f i.e. clear which is active low and click which is active high. And acceleration to wave forms of click and clear we can see that when click is enabling the circuit, clear is disabling the circuit and vice versa.

So each f/f should hold its previous o/p throughout the operation. Q0, Q1, Q3 is doing the same But not Q2.

Darnasinarendra said:   1 decade ago
Option B is correct since, the output of the D FF follow's the input i.e for CLK=1

i/p D=O o/p Q=0,
i/p D=1 o/p Q=1.

If you see the options, option B is incorrect because it's not following the i/p properly.

Hemant Kumar Rajyora said:   2 years ago
I think Q2 is not following D2 as Q2 is 1, when the positive edge comes that output must follow the input.

But here Q2 is 0 when the positive edge of the clock has arrived, it must be 1.

SAI said:   1 decade ago
Can anyone describe more clearly ?

As D2 is 1 the Q2 did came 1 then what is wrong in it?
(1)

Zarko Nozica said:   1 decade ago
Please explain what is the meaning of D = -1?

You probable meant 0? or what else?

Raajee said:   1 decade ago
According to definition f-f stores either 1 or 0 not -1.

Lala ji said:   2 years ago
@All.
D1=-1 is not correct.
that is D1=1.

Preyksha said:   1 decade ago
Please elaborate how Q2 is incorrect?

Zarko said:   8 years ago
Answer B is correct only if D0=0.

Zarko said:   8 years ago
Answer B is correct only if D0=0.


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