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1.5 to 3 MHz frequency doubler circuit
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SiliconWizard:

--- Quote from: Benta on December 27, 2018, 04:15:01 pm ---The comparator is unnecessary and just helps Maxim sell a device. An RC delay into a Schmitt trigger and then into the XOR is enough. You'll need to play around with the RC values.

--- End quote ---

True. Note that if you use a 74AUP1G86 (single gate XOR), it has schmitt trigger inputs, so no additional component is necessary.

Of course an RC delay is not that stable, especially temperature-wise, so you'll inevitably get some drift of the duty cycle, but that should be ok for the op's application.
ogden:

--- Quote from: Gandalf_Sr on December 27, 2018, 02:00:04 pm ---I have a design where a Cypress BLE module feeds I2S audio data to a TAS5755M TI Amplifier.  The problem is that the Amp needs an extra clock signal called MCLK of 3.072 MHz and it needs to be a doubled, synched multiple the I2S SCLK signal of 1.536 MHz.  I built a circuit like this...

--- End quote ---

You need tuned LC tank multiplier like http://electriciantraining.tpub.com/14181/css/Frequency-Multiplication-95.htm, fast comparator and divide by two flip-flop to generate 1x clock back from multiplied one
Gandalf_Sr:
Wow, great responses guys, thanks :D

I have played with the R1 C1 values but, as has been predicted, the results can drift or be inconsistent.

Now I have several choices to look at:
1. Use a 74AUP1G86 XOR logic IC with Schmitt trigger inputs
1. Use a 74HC4046A PLL IC which will need a divide by 2 circuit for the feedback loop, probably just a JK flip flop
2. Use a tuned LC tank multiplier but won't that produce a sine wave output?

I'm discarding the transformer rectifier option as too expensive and large.

I will order components for all 3 and test each one.

Thanks again.
ogden:

--- Quote from: Gandalf_Sr on December 28, 2018, 09:34:29 am ---2. Use a tuned LC tank multiplier but won't that produce a sine wave output?

--- End quote ---

Yes. That's why comparator was mentioned - to convert sine to square wave.
Gandalf_Sr:

--- Quote from: ogden on December 28, 2018, 09:40:59 am ---
--- Quote from: Gandalf_Sr on December 28, 2018, 09:34:29 am ---2. Use a tuned LC tank multiplier but won't that produce a sine wave output?

--- End quote ---

Yes. That's why comparator was mentioned - to convert sine to square wave.

--- End quote ---
Sorry, not fully awake yet  :P
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