Call for electronics engineers

[tormentor22]

Ok here is my prob,
am designing a high speed infrared link (at about 100Mbps) so i need an oscillator with equivalent freq (100Mhz) which isnt available the best that I could find for now is mch lower 25Mhz,, so can anybdy help me figure out a way to creat 100MHz from 25MHz ones?

Thanks in advance

[[XC] Lead Head]

http://www.alltronics.com/cgi-bin/it...MHz-Oscillator

Thats just the first hit on google, there were many more as well, they seem to be freely available though...

[W1zzard]

google for pll

[DeltZ]

Yeah.. I don't think you can make a high frequency oscillator using just lower frequency ones...

[tormentor22]

google for pll

Thx w1zzard..

http://www.alltronics.com/cgi-bin/it...MHz-Oscillator

Thats just the first hit on google, there were many more as well, they seem to be freely available though...

If i could find a 100MHz oscillator to buy i wouldnt have posted

Yeah.. I don't think you can make a high frequency oscillator using just lower frequency ones...

Actually u can,,, this is what i figured out,, well ure PC works with low freq oscillators which drives few GHz CPU and components, that is done using PLL (phase loked loop) which is a form of freq multiplier.

[DeltZ]

Sounds like you'll need a PLL chip then. I thought you meant you wanted to make 100MHz by combining 25MHz ones. But sure, if you got a 25MHz reference and then work out how to use a PLL chip, you're set. No idea about PLL though.

[[XC] Lead Head]

http://cgi.ebay.com/100MHz-ECLIPTEK-...3%3A1|294%3A50


is there any reason you can't use e-bay?

[persivore]

Farnell carry a number of 100MHz crystal oscillators (or at least they do in the UK (http://uk.farnell.com/jsp/search/bro...scillator&Ntx=). Similar products should be available from your countries local farnell distrobution center to avoid international shipping.

Do you have a link to what you're trying to do? Using clock speeds as high as 100MHz is going to require some careful board layout. Breadboard (and probably stripboard too) will have problems carrying signals around at 100MHz due to the various parasitics, so you will probably need a PCB.

Edit: You might also have trouble running infra red devices at 100MHz. The fastest IR emitter I can find has rise/fall times of 12ns, which would result in a speed of around 83MHz. There are probably faster devices available, although I've not searched for them. You would probably want to go for a device significantly faster than the speed you want to run at tho, to allow for the added delays encountered from driving the IR emitter and any associated signal processing.