# Method and circuit to reduce Jitter?

• posted

Hi,

I am an electrical engineering student and I am interested in circuit design. Unfortunety I am not so familiar with analog design. Therefore I want to place my question here in the newsgroup:

Is there a method to reduce jitter without the use of PLL? Where can I find sophisticated circuits for this?

Any help, hints and comments are highly appreciated.

Greetings Simon

• posted

Before trying to give specific advice, I'll point you at a decent introduction to the subject:

After that, we'd need a lot more information - PLLs have jitter that is often worse than the driving input for instance, so they are not a panacea.

Cheers

PeteS

• posted

Reduce jitter of what?

John

• posted

pre-exam ?:-)

...Jim Thompson

• posted

I used to actually enjoy Exam Week. About an hour before each test, I'd sit under an oak tree, skim the textbook, take the test, and then I'd have the rest of the day off. If I was in a playful mood, I'd finish the test in a half hour and leave, which would freak everybody else out and boost me on the curve. Having done electronics since I was a kid, I knew what was important. To most of the other guys, all this was a maze of equations without a lot of real meaning... I was the *only* electronics hobbyist in my EE class. I took one electrical machinery class, with an especially ornery instructor, where class average on quizzes was 15%, so my 50% was an A.

He'd lecture:

"OK, will this motor rotate clockwise or counterclockwise? Show of hands? OK, next subject..."

John

• posted

You should have begun with Google.

1. Pay some attention to the feedback filter.

Don

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There was a kid in my school who did that.. When the results can back it he would get 150% right because he'd answered all the questions not just the 4 out of 6 that you were meant to.

• posted

Most times when I've had an exam where it was, "answer x of y questions," if you answered more than x it was the grader's call on which x of y they'd grade, so you'd better be quite certain you answered them all correctly.

John probably had pretty good exams... ones where, if you truly understood the material, you could answer all the questions quickly, whereas those who needed to use the exam as "brief periods of intense learning," as a former professor of mine used to call them :-), could use up all the allotted time.

Better professors would also sit there and work through the exam themselves to make sure there weren't any errors or ommissions that had slipped in at the last minute... that was a much better scenario than when there was some critical piece of information missing -- but you thought you just weren't getting it somehow, and had wasted a bunch of time trying to figure it out --, and someone would finally go up and ask the prof. who'd then tell the class, "Oh, sorry! Use such and such a value..."

• posted

My first college room-mate was a mechanical engineering major. As such, he was required to take a Freshman course titled "Engineering Graphics", which had been taught by the same ancient professor for decades. The professor allowed students to bring any materials they wished to the final exam. So, of course, the engineering fraternity sold a bound volume of all the problems ever given in the EG finals, complete with worked out solutions.

There were some humorous twists: some of the solution sheets included lines included like "Drop your pencil and pick it up", Lean back and stretch" or "Smile and wave to the proctor". Of course, you were supposed to perform those acts, not copy them blindly into the test papers.

• posted

LOL,

Wonder if any clueless student ever did copy them blindly. The prof probably wondered, "What the h__??"

daestrom

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I wonder what the profs thought when a whole classful of students would drop their pencils, or stretch, or smile and wave, simultaneously. ;-)

Cheers! Rich

• posted

Reminds me when I was a student...the landlady's kid was a brat. He persuaded one of my friends to do his homework. Friend wrote the answers into his exercise book in pencil so kid could go over it in ink. One day kid came home and announced he was in big trouble and had been sent to see the head. It turned out that my friend had written "teacher has cheesy feet" right in the middle of the previous nights homework...and the brat had gone over it in ink so it was in his own writing. :-)

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Repeat out loud

Wa Tana Siam

Wa Tana Siam

etc

• posted

I don't remember that one. But I do remember the Order of Siam in Boy Scouts...

Oh Wa Ta Goo Siam

...Jim Thompson

• posted

"Simon" schreef in bericht news:45ae158b\$0\$5720\$ snipped-for-privacy@newsspool3.arcor-online.net...

What have you done yourself before asking here? A lot of circuits introduce jitter in a lot a signals and PLL is one of them. What circuit are you talking about? Some years ago Electronics World had an article on reducing jitter in signals. Being an electrical engineering student you should be able to find this (and a lot more).

petrus bitbyter

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I remember that one from an old Odd Couple episode.

• posted

and the OP hasn't really explained the origin of the jitter. Could be lots of ways of reducing it at source.

• posted

Simon, Your question should also explain a few more thigs:

1. which is the amplitude, the frequency and the shape of the signal having this jitter
2. at least which is the magnitude order of your requested jitter
3. which is the circuit topology which is carrying this signal (IQ, bipolar, unipolar etc)

PLL in 90% of the situations are adding a bigger jitter than a clean low noise oscillator output may have. Any sophysticated circuit has a limited chance to work opposed to a simple circuit. Remember one thing when you'll become engineer and you'll have a lot of employeers on your hand: keep things simple in your design and in your relations with other people.

greetings, Vasile

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