[time-nuts] Slightly OT: interest in a four-output, ultra-low jitter, synthesizer block?
wb6bnq at cox.net
Thu Jan 25 15:12:50 EST 2018
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
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,
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 ?
>> 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:
>>> 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.
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