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What's the best topology for Ku band PLL?

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zeshan102

zeshan102

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i want to design a Ku band synthesizer what will be best topology for getting best phase noise is it possible to use IC for sysnthesizer and then use FET multiplier to upconvvert to Ku band how much better phase noise req before multiplier i am looking around 90 dBc at 10 Khz.


Thanks
 

Re: Ku band PLL

is ur design is on the chip level or an integrated synthesizer ??
 

    zeshan102

    zeshan102

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Re: Ku band PLL

i think its integrated not chip level i am not designing IC . but can u explain more what do u mean by integrated or chip level
 

Re: Ku band PLL

I mean that will u design ur PLL using ICs already exist in the market or u will design ur own IC ??
 

Re: Ku band PLL

Your Phase noise at 10 kHz will be heavily dependent on the loop filter bandwidth that you choose. Ku Band is 12 to 18 GHz, which is pretty high. Multiplying the output frequency to get to 12 GHz in not the way to go, as the phase noise will degrade by ~ 6 dB per factor of 2 (Multiplying by 16 will cost you 24 dB of phase noise). Perhaps you could use an external divide stage after the VCO, before the prescaler, to get the RF frequency down to the range that an integrated PLL will accept.

Dave
 

    zeshan102

    zeshan102

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Re: Ku band PLL

I think that National/Analog/Perigrine all go up to ~ 6 GHz or so. You might want to look at parts from Hittite, they may be able to put together a discrete solution. This is a challenging task, to be sure.

Dave
 

Re: Ku band PLL

Hello Dave;
Do you mean that in Ku band engineers should design discrete PLL using transistors?
 

Re: Ku band PLL

Well, Ku band is where MMIC stuff starts to happen, where everything in transmission line and on a ceramic substrate. I'd be tempted to design the VCO discretely on a substrate, and use a discrete prescaler to take the VCO output down to something that a Multi-modulus prescaler can accept. Id be even more interested in buying one off the shelf because of the amount of work it could take to build one.

Hittite (https://www.hittite.com/index.cfm) has some applicable parts, but they were simply the first to come to mind.

Dave
 

Re: Ku band PLL

Look at **broken link removed**
 

Re: Ku band PLL

Hello;
Zeshan102 wrote:
unable to open the website is this address correct?
Click to expand...

But I opened the website.Copy the URL address in your explorer.
 

Re: Ku band PLL

The way people have been doing it for decades is to have an oscillator at KU band, and a sampler driven by someting like a 100 MHz xtal oscillator, and close the loop on the sampler output.

Nowadays, you can get a higher xtal drive frequency, like maybe 250 MHz, to give you a little more tuning range before aliasing.

It is hard to beat this old school style of circuit, since the RF phase sampler has much lower inherent phase noise than a digital gate does.
 

Re: Ku band PLL

Is there a significant difference in phase noise between these structures :
1) design a L-band PLL and the multiply it up to ku-band or
2) design a ku-band pll directly?
I think that the first one will be better in phase noise. Isn't it?
 

Re: Ku band PLL

i have realize ku band pll using hittte vco HMC529LP5 by using its divide by 4 pin to lock pll chip ADF4153 at around 3 ghz.
 

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