[time-nuts] Slightly OT: interest in a four-output, ultra-low jitter, synthesizer block?

John Ackermann N8UR jra at febo.com
Thu Jan 25 15:23:51 EST 2018


Hi Bill --

And that's exactly what I *don't* want to do. :-)  The reason is that I 
have several different projects in mind (and everyone else will have 
their own requirements) and only want to deal with the difficult package 
once.

The idea is to make a minimal carrier to deal with the tiny part and 
six-layer board.  Then all the ancillary stuff (including the MCU that's 
needed to program the chip) goes onto the board designed for that 
project.  This isn't intended to be a finished product, just a building 
block.

73,
John
----
On 01/25/2018 03:12 PM, wb6bnq wrote:
> Hi John,
> 
> Thanks for the response.  Here is my 2 cents:
> 
> Well, due to the level of difficulty in chip mounting, I would prefer to 
> see a complete project. I.E., power supply for a single input of 12 
> volts and regulators the necessary chip values, proper input protection 
> for the 10 MHz input level and single ended outputs of the appropriate 
> levels (I am assuming more than 3 volts) or an amplifier stage for 
> arriving at such.  Equally have RF connectors (SMA would be good) on the 
> board perhaps.
> 
> Of course as cheap as possible, hi hi.  A carrier board arrangement 
> would be useless to me.  My application would be to provide signals for 
> things like my Quicksilver SDR receiver, among other uses.
> 
> If you are interested, I can show you a nice little ABS (I think) box 
> that has EMI built-in that I used for a project that should be more than 
> large enough for your needs.
> 
> Thanks for reading,
> 
> 73....Bill....WB6BNQ
> 
> 
> John Ackermann N8UR wrote:
> 
>> Hi Bill --
>>
>> I should have been more clear: this design will be for a simple case: 
>> one reference clock input, four outputs.  The chip can do all sorts of 
>> fancy tricks, but I'm looking for a source of four low jitter outputs 
>> derived from a 10 MHz external reference (not using crystal or 
>> on-board oscillator).  Many of the pins are unused in that configuration.
>>
>> I'm not looking to make a universal carrier for the chip, but to meet 
>> what I suspect is a common time-nut/ham radio desire for a clean 
>> multi-channel synthesizer.
>>
>> On 01/25/2018 02:02 PM, wb6bnq wrote:
>>
>>> Hi John,
>>>
>>> After looking at the data sheet, it seems way more involved then just 
>>> making a carrier board for it.  Besides the power supply 
>>> requirements, various design selections would dictate different 
>>> circuit layouts for different purposes.  Even trying to do a general 
>>> purpose application would possibly require having several different 
>>> output configurations and possibly a couple of input configurations 
>>> as well.  That would imply a rather detailed PCB and that chip 
>>> package style is a serious pain in the ass for [what amounts to] 
>>> hobbyists.  So it would seem the logical course would be to do 
>>> serious design application and see if an in-house component mounting 
>>> job would be feasible.
>>>
>>> I notice that the data sheet says the jitter specs are only best when 
>>> using The internal crystal oscillator frequency between 48 and 54 
>>> MHz. It was unclear to me that the same would apply to using the 
>>> non-crystal inputs.
>>>
>>> Perhaps you could indicate what you are attempting to do with it and 
>>> how you are going to accomplish your goals ?
>>>
>>> 73....Bill....WB6BNQ
>>>
>>>
>>> John Ackermann N8UR wrote:
>>>
>>>> After the recent discussion about Silicon Labs clock generators, I 
>>>> looked at their Si5340A part and think it will be useful for a ham 
>>>> radio project I'm working on.  While it can do other things, for my 
>>>> use it would use a 10 MHz input clock and generate 4 independent 
>>>> outputs in the range of 100 kHz to 1028 MHz.  Its jitter is <100fs, 
>>>> which translates to "not bad" phase noise.  Here's the data sheet if 
>>>> you're interested:
>>>>
>>>> http://www.silabs.com/documents/public/data-sheets/Si5341-40-D-DataSheet.pdf 
>>>>
>>>>
>>>> The challenge is that the chip is a 7x7 mm 44-QFN package and really 
>>>> wants to be put on a six-layer circuit board.  That's doable, but 
>>>> challenging, for home assembly.
>>>>
>>>> Rather than designing the chip into a larger circuit board, I'm 
>>>> thinking of doing a small "carrier" board that would include just 
>>>> the chip and critical bypass caps and have headers to plug into the 
>>>> main board. Then, you could just drop the carrier into a 
>>>> project-specific board and not have to worry about the complex 
>>>> layout and mounting.  I have a contract manufacturer who can build 
>>>> these up, if there's enough quantity to justify the setup cost.
>>>>
>>>> If you'd be interested acquiring in one or more of these, please 
>>>> drop me a line off-list (jra at febo dot com).  I don't think this 
>>>> will be a TAPR project, but if there's enough interest to build 25 
>>>> of these carriers, I can probably make that happen.  And remember -- 
>>>> this is just the chip; you'll need to provide the rest of the circuit.
>>>>
>>>> John
>>>> _______________________________________________
>>>> time-nuts mailing list -- time-nuts at febo.com
>>>> To unsubscribe, go to 
>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>> and follow the instructions there.
>>>>
>>>
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at febo.com
>>> To unsubscribe, go to 
>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to 
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.


More information about the time-nuts mailing list