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I need to generate a 150.012MHz signal. I am going to this with a PLL for RF purposes, so I am thinking to buy a 10Mhz osc with a sine output, will this work with all PLLs? as they are digital I'm not pretty sure. Or should I buy an square oscillator?

Thank you in advance.

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  • \$\begingroup\$ What phase detector do you plan to use for your PLL? \$\endgroup\$
    – The Photon
    Commented Jul 6, 2015 at 16:52
  • \$\begingroup\$ I am planing to use this PLL silabs.com/Support%20Documents/TechnicalDocs/si4133.pdf it already has a phase detector \$\endgroup\$
    – José Chávez
    Commented Jul 6, 2015 at 19:10
  • \$\begingroup\$ That datasheet isn't very informative. It's clear that one option is CMOS levels, so if you can, I'd go with a reference source with CMOS levels. If you would really rather use a sine-output oscillator, it looks like it'd probably work (as long as you ac-couple and meet the sensitivity requirement on pg 8), but it would be a good idea to test it on a demo board before comitting to the design. \$\endgroup\$
    – The Photon
    Commented Jul 6, 2015 at 19:21
  • \$\begingroup\$ Yes. I'm doing a demo board befor the final design but the problem is I have to wait several weeks to have the component. On pg 4 there is a -0.3V limitation for all the inputs, including Xin, so I was confused. \$\endgroup\$
    – José Chávez
    Commented Jul 6, 2015 at 20:12
  • \$\begingroup\$ Since they are recommending users to ac-couple the input, there is probably an internal bias circuit to set the dc level at the XIN pin to around VCC/2. \$\endgroup\$
    – The Photon
    Commented Jul 6, 2015 at 20:29

1 Answer 1

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The FAQ @ https://www.silabs.com/Support%20Documents/TechnicalDocs/Si41xxFAQ.pdf

States that either a sine wave or a square wave is acceptable.

"Q: Should the reference source have a sine wave or a square wave output? A: The reference source can have either a square wave or sine wave output. The reference amplifier has a large gain that converts the incoming sine wave to a square wave. Therefore, both sine and square wave references are processed identically."

From the data sheet the signal should be at least 0.5V p-p in amplitude and coupled with a 560pF capacitor.

kevin

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  • \$\begingroup\$ I didn't know there was a FAQ document. Thank you! \$\endgroup\$
    – José Chávez
    Commented Jul 6, 2015 at 20:07

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