Hello:
I was playing with some flip flop circuit, then instead of Qbar I connect Q to input of last stage , so I got spikes !!




is just spikes !!

 

Scope input is AC coupled?

 

I;m sorry. I don't understand , I just plot this circuit, if I change the output from Q into Qbar the output is like this

 

Simulation or real ?

 

I was playing with some flip flop circuit, then instead of Qbar I connect Q to input of last stage , so I got spikes !!

You need to provide us with more information.

What is the logic family? What are nodes n1 and n2? What is the supply voltage?

Not many logic families will toggle at GHz frequencies.

If we assume that the flip flops initialize with Q=0, what will the flip flops do with logic 0 on the inputs?

You should probably stop using simulators until you have a better understanding of fundamentals.

 

There are no questions in posts 1 and 3. What is it you want to know?

ak

 

You need to provide us with more information.

What is the logic family? What are nodes n1 and n2? What is the supply voltage?

Not many logic families will toggle at GHz frequencies.

If we assume that the flip flops initialize with Q=0, what will the flip flops do with logic 0 on the inputs?

You should probably stop using simulators until you have a better understanding of fundamentals.

I thought its just a simple and not need much explanation
- V is 1.5v
- its toggle in seconds case.
- its not logic IC, its logic build from cmos

please if you have document about these logic and freq dividers I'm appreciate

 

There are no questions in posts 1 and 3. What is it you want to know?

ak

need to know as in Post 1 and 3... why the output appears as spikes if I change to output of flip flop from negative to positive

 

If you built the flipflops out of logic gates as you said, then we *really* need to see the schematic.

Why do you think the output you have is wrong? What output did you expect to see?

ak

 

its not wrong, but spikes instead of rectangular waves !!

 

- its toggle in seconds case.
- its not logic IC, its logic build from cmos

In the first case, you're basically feeding Q to the D input. What do you expect a D FF to do in that case? Not knowing what n001 and n002 are, I can't even guess what the spikes are from.

Since you're designing the flip flops from MOSFETs, we need to see the schematic.

 

I know what the spikes are from, but it is too difficult to discuss without the actual circuit schematic.

ak

 

Considering the magnitude and frequency of the spikes, I think I know where they're coming from too.

 

Have you decoupled the circuit ?

 

What good is a 60mV signal when your threshold is 750mV?