Perfect High Speed Clock Generation

Thread Starter

Manish Chowdhary

Joined Jul 29, 2017
10
One of the most common method for generation of clock signals to run a high speed synchronous circuit is, crystal oscillator coupled with VCO. I also hear about SAW oscillators.

Wondering, which is the most reliable(least variation in periodicity) method for generating a high frequency clock?
 

andrewmm

Joined Feb 25, 2011
1,751
We love the "what's the best" type questions, they can go on for ages.

The ultimate answer is " the minimum that meets your needs " is the best.

Now what are your needs ?

Long term, least variable would be an atomic locked unit, such as a GPS receiver.
short term, a TCXO .

The reason for the VCO in your example would be to either multiply the raw clock up , or to lock the clock to an external reference, such as a data stream.

SAW's, are really crystals, but instead of the bulk effect, they use an etched array on the crystal,

you will also hear about MEMS clock generators, fundamental et all clock generators.


Unless you are in very specialised area of work, in which case I'd suggest you need to know more about the parameters you want,

an standard "crystal" oscillator from any reliable source will do you.
 

Thread Starter

Manish Chowdhary

Joined Jul 29, 2017
10
I am not a circuit designer, but as a firmware engineer, I work on enabling the external reference clocks on a different part of the circuits. Over the years, I have seen the reference clock generation circuits change a lot. My question was more out of curiosity; You very rightly said that best is the one that meets one's need.

Going by the definition of TCXO, it is best suited for high-temperature environments, so it would be best for specific use cases, while the atomic clock would be more suited for some other need.
 

dl324

Joined Mar 30, 2015
13,087
I'd use a SAW because it will be operating at it's fundamental frequency instead of a higher order harmonic. Do the homework and see which has better accuracy and stability.

If you don't want to do the research, the SAW resonator will probably be better and they don't cost that much more than a regular crystal.
 
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