[time-nuts] up converting 10MHz to 20MHz

[Magnus Danielson]

Hi Lincoln,

On 12/10/2014 03:49 AM, Dave M wrote:
> lincoln wrote:
>> Hello,
>> I'm having a dumb idea, I have an MCU that uses a 20 MHz VC-TCXO. The
>> micro, among other things, runs a loop and correct the oscillator by
>> using a 1pps from a gps. I have a 10 MHz mv200 that I would like to
>> try to use. I've got the control voltage handled but i will need to
>> multiply its output up to 20 MHz. What would be the most kosher way
>> do do this? I was having a look at Cypress's CY22381 because I have
>> the programmer but the chips are not widely distributed. But nether
>> are mv200's Silicon labs also make all kinds of clock chips as well.
>>
>> What do you guys think? What would be the best way to scale up by X
>> 2? lowish phase noise / jitter is important, low power is not.
>>
>> Thank you,
>> Lincoln
>
> A couple ways to go on a doubler.
> Minicircuits makes a line of frequency doublers, such as the SK-2, RK-2,
> RK-3, etc.  You could also roll your own using a balun and a diode
> bridge (http://www.techlib.com/files/diodedbl.pdf).  Insertion loss is
> pretty hefty in both solutions, so you''ll need to follow with a 10-15db
> amp.

As you is then going to use it for digital circuits, don't forget to 
square it up using a gainstage, look at the Wenzel sine-2-square, or the 
input stage of TADD-2 (which is the Wenzel design), and then run it 
through a pair of inverters before it his the MCU.

If you already have a VC-TCXO, then you could divide it down to 10 MHz, 
then use a digital phase comparator and a PI-integrator (2 resistors, 1 
capacitor and an op-amp) to create the EFC for the VC-TCXO.

Cheers,
Magnus