4 Phases Non-Overlapping Clock Generator

[a7m3d]

How to implement/design 4 phases non-overlapping clock generator?
I found this figure without enough details about the implementation. I need a clear reference to build the 4 phases non-overlapping clock generator or in general n phases non-overlapping clock generators for example a 3 phases non-overlapping clock generator.

 

[BradtheRad]

Your shift register is a start. By adding the right logic gates, a single pulse train is rotated through all outputs.



By adjusting the clock's duty cycle, you change the spacing between the outputs.

This illustrates a concept for 2 outputs. It should be easy to extend it to 4 outputs.

 

[a7m3d]

The feedback between the 2 flip-flops reserves the state of the output of the 2nd flip-flop. If Q2=0: -> D1=0 -> Q1=0 -> D2=0.
I do not know if I missed something. I will appropriate any help. Thanks.

 

[BradtheRad]

To get four outputs, add two more flip flops.

 

[a7m3d]

The output of the 4 flip flops is zero, they reserve this state every cycle.

 

[BradtheRad]

It is plain to see why you do not get the same results as my simulation. You must add the NOR gates as shown in my post #2.

 

[a7m3d]

The problem is not is the NOR gates, the output of the 4 D flip-flops is the same Q1=Q2=Q3=Q4=0. CLK NOR Q(1 or 2 or 3 or 4) will give the same result which is the CLK complement. I do not know if I missed something. Thank you very much.

 

[BradtheRad]

The problem is not is the NOR gates, the output of the 4 D flip-flops is the same Q1=Q2=Q3=Q4=0. CLK NOR Q(1 or 2 or 3 or 4) will give the same result which is the CLK complement. I do not know if I missed something. Thank you very much.

Yes, now I am getting a similar result with my simulation. It does not know what initial state to assign the long wire going the length of the circuit.

I tried a few things, attempting to obtain a sensible output. It worked when I put 2 inverters in a row.



Simulators are prone to these types of errors.

 

[D.A.(Tony)Stewart]

You see the ways to make like a Johnson Counter sequence .
Synchronous counter decoder, rotating serial shift register.

Unknown Setup/hold times can produce unpredictable results.

But, if you wanted the edges to be non-overlapping as well as each state, then there must be a dead-band between output phases, such as used in full bridge drivers to prevent shoot-thru.

If that were the case, a monopulse or one-shot on the active clock edge can be used to AND or disable the outputs.

 

[mtwieg]

Here's an example based on a johnson counter. The frequency of the output will be half the LO frequency.


The duty cycle of the LO (the reference clock) should be 50%. If your clock source is not 50%, then use another flip flop as a frequency divider.