Electronics > Projects, Designs, and Technical Stuff
Level-translate the output of a TCXO crystal oscillator module
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xaxaxa:
PL133-37 clock buffer can accept clipped sine wave input, and phase noise is reasonable at -100dBc at 30Hz offset.
Leo Bodnar:
PL133-37 residual phase noise is much lower. -100dBc/Hz at 30Hz is the Micrel's source phase noise. 
PL133-37's noise will probably be around -130..-140 mark.
Leo

--- Quote from: xaxaxa on August 23, 2018, 02:18:21 pm ---PL133-37 clock buffer can accept clipped sine wave input, and phase noise is reasonable at -100dBc at 30Hz offset.

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Leo Bodnar:
I have measured PL133-37 residual PN a few days ago - it is about -143dBc/Hz at 30Hz offset with 10MHz carrier.
-150dBc/Hz at 100Hz
-160dBc/Hz at 1kHz+
Not the sharpest tool in the box but cheap and cheerful.
Leo


--- Quote from: Leo Bodnar on February 15, 2019, 05:05:51 pm ---PL133-37 residual phase noise is much lower. -100dBc/Hz at 30Hz is the Micrel's source phase noise. 
PL133-37's noise will probably be around -130..-140 mark.
Leo

--- Quote from: xaxaxa on August 23, 2018, 02:18:21 pm ---PL133-37 clock buffer can accept clipped sine wave input, and phase noise is reasonable at -100dBc at 30Hz offset.

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nick_d:
Regarding buffered vs unbuffered. If you ordered the 1G04 then it's in a pretty recent CMOS technology so it will be extremely fast. In that case, you can get away with buffered for this sort of thing. And so you will not need as big an input swing. What the buffering does is simply increase the gain of the inverting amp, by putting more inverting amps in series -- each one will have a gain of say 10 to 100 so with 3 of them in series you have a gain of 1000 to 1000000 approx. This is enough to cause clipping and give you a square wave which is what you want. The reason you would use the unbuffered amp is when you're concerned about the delay through the extra 2 gates, causing instability in your feedback network. That's unlikely to be a problem here. I would have to analyze the proposed circuit to be sure. But if you are concerned, you can make your own buffered amp with 3 x unbuffered and tap the feedback from the first stage.
cheers, NIck
Leo Bodnar:
These days you might want to use something like http://www.ti.com/lit/ds/symlink/sn74lvc1gx04.pdf
Leo

--- Quote from: nick_d on February 23, 2019, 11:18:13 am ---if you are concerned, you can make your own buffered amp with 3 x unbuffered and tap the feedback from the first stage.

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