Frequency multiplier (x2)

F

fabricioandd

New Member
Hi,

I am trying to design a simple frequency multiplier using CD4046. Since I don't have the ICs I've been trying to simulate on LTSpice. It's a simple circuit with a feedback loop with a D flip-flip which divides the frequency by 2. Therefore, I expect the CD4046 output signal will have its frequency be multiplied by 2.

However, it does not work. I am not sure whether the simulation is not working due to the non-official CD4046 model or if the circuit is wrong.

I would really appreciate any help.

Thanks in advance.
 

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Connect the D type Q directly to pin 3; the intermediate components are probably messing things up, especially such as the 10 Ohm resistors!

What is the input frequency?
 
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Why do you expect that there is such a thing as an official model. Neither Linear Technology, nor Analog Devices EVER made a CD4046. Furthermore, there is no authoritative source for any device models that did not originate from either Linear Technology or Analog Devices. This includes pretty much every BJT, diode, and MOSFET. As you can tell from the change logs, even the official source makes mistakes. Please discard your rose-colored glasses.
 
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rjenkinsgb said:
Connect the D type Q directly to pin 3; the intermediate components are probably messing things up, especially such as the 10 Ohm resistors!

What is the input frequency?
Click to expand...
Thanks, I think you are right!

I've tested this design by just wiring VC0out to CompIn and it works. There must be an issue with this intermediate components in the feedback loop. By the way, the frequencies tested ranged from 5Hz to 5KHz.
 
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Thanks! at least I've found electro-tech-online.com by searching for this IC model and maybe it works in some specific cases.

https://www.electro-tech-online.com/threads/new-spice-model-for-cd4046b-phase-locked-loop-ic.149093/
 
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Additionally;
The loop filter values are waaaaay too large. I ignore how the simulation handles this, but…A real world circuit will exhibit a long setting time.
Reduce them by a factor of 10. At least.
 
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