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Use of oscillator for 100MHz signal generation

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rf1008

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Dear all,

I need a signal near 100MHz,the general method is to design with PLL.But, my requirement of frequency stability is not strict,20ppm or 50ppm is accepted,also my requirement of PCB size is strict.


1)my first choice is to find a fully integrated IC including PLL and VCO, and N/R divider is also in-chip,so that the output signal will be ok once VCC is connected correctly.
Would you please kindly advise some part like that for me? thank you!

2)My second choice is to use oscillator directly,such as TCXO which has 4 pins(VCC/GND/EN/OUTPUT) .It's not a standard or perfect design, but i'll use it when my first choice could not be reached.
Oscillator output is squarewave and need to be filtered enough for harmonics rejection. or, is there anything i should consider? thanks.

My operation frequency is in 80~120MHz and only one frequency point is ok, thanks a lot!
 

rf1008 said:
Dear all,

I need a signal near 100MHz,the general method is to design with PLL.But, my requirement of frequency stability is not strict,20ppm or 50ppm is accepted,also my requirement of PCB size is strict.


1)my first choice is to find a fully integrated IC including PLL and VCO, and N/R divider is also in-chip,so that the output signal will be ok once VCC is connected correctly.
Would you please kindly advise some part like that for me? thank you!

2)My second choice is to use oscillator directly,such as TCXO which has 4 pins(VCC/GND/EN/OUTPUT) .It's not a standard or perfect design, but i'll use it when my first choice could not be reached.
Oscillator output is squarewave and need to be filtered enough for harmonics rejection. or, is there anything i should consider? thanks.

My operation frequency is in 80~120MHz and only one frequency point is ok, thanks a lot!
Click to expand...

Hi
you have an another choice and its DDS!
because I think you can't find PLL in this frequency.
 

You can search for datasheets on some IC's using this search line: "mhz vco filetype:pdf" or maybe "mhz pll filetype:pdf"
(works in google and some other search engines, without " of course). I've found many chips this way.
 

For a 50 ppm oscillator at 100 MHz, you can use an overtone quartz oscillator. Digi-key even offers miniature hermetic modules that would fit on your small PCB.
 

You've got to read this ebook. **broken link removed** were all the details you need for the requirements of your PLL. You can adjust your PLL, just follow the diagram so you can get your desired frequency. Hope it helps!
 

rf1008 said:
Dear all,

I need a signal near 100MHz,the general method is to design with PLL.But, my requirement of frequency stability is not strict,20ppm or 50ppm is accepted,also my requirement of PCB size is strict.


1)my first choice is to find a fully integrated IC including PLL and VCO, and N/R divider is also in-chip,so that the output signal will be ok once VCC is connected correctly.
Would you please kindly advise some part like that for me? thank you!

2)My second choice is to use oscillator directly,such as TCXO which has 4 pins(VCC/GND/EN/OUTPUT) .It's not a standard or perfect design, but i'll use it when my first choice could not be reached.
Oscillator output is squarewave and need to be filtered enough for harmonics rejection. or, is there anything i should consider? thanks.

My operation frequency is in 80~120MHz and only one frequency point is ok, thanks a lot!
Click to expand...


Hello.

Yes, an Integrated circuit do exist that can provide you exact 100MHz clock output..
Please refer to
CDC421100RGER
CDC421100RGET

Both of them requires, 33.333MHz crystal and outputs 100.0MHz clock.
They have very low jitters and can be used for stable frequency requirement.

Please refer to the datasheet. Higher frequencies can also be achieved by using the other parts from this series.

Thank you.
Salman
 

Use a TCXO and a nice filter. 33.33MHz crystal will do, you can put a filter at the 3rd harmonic.




I see you suggested this originally.
 

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