# JK FLIP FLOPS

#### sxy

##### Member
HI

Figure A of Question 6 shows a diagram of a circuit made up of JK FLIP FLOPS components, which respond to the
.decrease of each CLOCK

For the SI input, the DATA information signal, shown in Figure B, is provided .
Assume that at time T = 0
Q1 = Q2 = Q3=0.
A. Indicate the purpose of the circuit shown in Figure A.(In the file attached).
B. Indicate a possible use of the circuit shown in Figure A.
Thanks a lot

#### Attachments

• JK FLIP FLOPS.pdf
274.2 KB · Views: 60
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#### AnalogKid

##### Well-Known Member
This is not a free homework service. Show us your answers and how you derived them, and we will advise.

ak

#### sxy

##### Member
Hi
I drew the answer to the third question:
the waveforms of Q1;Q2; and Q3.
thanks a lot

#### rjenkinsgb

##### Well-Known Member
I drew the answer to the third question:
the waveforms of Q1;Q2; and Q3.
Wrongly; remember that setup is creating a shift register.

#### sxy

##### Member
So can you drew the right waveforms of Q1;Q2; and Q3?
In all cases j1=j2=j3=1
and k1=k2=k3=0
so q should be high.
Why am I wrong?
j=1 and k=0 is reset and not setup up as you said.
thanks a lot

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#### rjenkinsgb

##### Well-Known Member
The inputs of each are fed from the preceding stage.

When does J2 become 1? So when can Q2 become 1....

#### sxy

##### Member
It happens at the same time because they have the same clock.
That is exactly what I drew.
All the FF turn to 1 at te same time as I drew.

#### DrDoggy2

##### Member
they do not.
look at what each value of j,k & q is when that clock is pulsed

#### sxy

##### Member
So can you please drew the right waveforms of Q1;Q2; and Q3?
thanks a lot

#### rjenkinsgb

##### Well-Known Member
There is no point someone drawing it if you do not understand why they work as they do.

The clock edge is an instantaneous event.

At that instant, J is high (and K low) for the first stage only.

It's Q [Q1] changes after the clock edge; it is cause-and-effect; the effect cannot take place until after the cause has.

#### sxy

##### Member
I fixed the error in the new attachment.
Can you check if this is true?
Thank you

#### Attachments

• jk flip flop2.pdf
580 KB · Views: 19

#### sxy

##### Member
So you mean that after the first CP j1=1 and q1=o and only after the second CP q1=1?
thanks a lot
CP=clock pulse

#### rjenkinsgb

##### Well-Known Member
You were correct with the modified sketch.

Q (and /Q) change immediately after the clock edge; typically a few nanosecond in real devices.
The J & K (or D for D type) inputs need to be valid for typically a few nanoseconds before the clock edge, to be accepted.

So, the input data is shifted through one stage per clock pulse; that's what a "shift register" does:

#### sxy

##### Member
You changed the DATA something that is is not allowed to do.
I drew only q1 q2 and q3.

#### sagor1

##### Active Member
You changed the DATA something that is is not allowed to do.
I drew only q1 q2 and q3.
Your own PDF (second one) is showing the same effect, the input data is being shifted by each stage as it is clocked. Just happens you have 3 stages instead of 4 as shown by RJen. Number of stages is irrelevant, it is the concept of shifting that is being shown.

#### sxy

##### Member
DATA is a given thing and is part of the question and therefore must not be changed.

#### rjenkinsgb

##### Well-Known Member
You changed the DATA something that is is not allowed to do.
That is a diagram showing how a shift register works, using JK type flip flops.

It's not an answer to your homework, it's education; the data at the input (whatever it is) will move one stage along with each clock cycle.

More examples:

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#### Papabravo

##### Well-Known Member
You changed the DATA something that is is not allowed to do.
I drew only q1 q2 and q3.
Why not? Is that a realistic occurrence in a real system? What would be the point in filling up a register with either 1's or 0's and not letting the input change. Where did you acquire such a quaint notion?

#### Dr_Doggy

##### Well-Known Member
That is a diagram showing how a shift register works, using JK type flip flops.

#### sxy

##### Member
Hi
A. What is the purpose of this system?(In the attached file).

B. The table below shows the initial state of the input IN and of the outputs Q0, Q1 and Q2.
Copy to your notebook the table and complete in it the condition of each of the finds for
Knocks 1-5.

C. Copy to your notebook the clock pulses in Figure B and draw, one below the other, the shape
Wave at each of the outputs Q0, Q1, Q2, for pulses 1–5.

#### Attachments

• Image_0008920220716213136.pdf
474.2 KB · Views: 15

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