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Phase-locked loop IC recommendation

Discussion in 'Electronic Design' started by Paul Burridge, Feb 5, 2004.

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  1. Hi,

    If all else fails I may have to implement this project with a PLL
    which will need to generate 30-50 channels @ 10Khz spacing in the
    region of between 40.5 - 41Mhz.
    Any suitable devices/manufacturers spring to mind?


  2. Tim Wescott

    Tim Wescott Guest

    Motorola had some good ones a few years back -- I'm not sure if they still
    do, or if it'd be Mot or On that would have gotten them. Look for
    "synthesizer" though -- "PLL" gets you discussions of microprocessor clock
  3. Tim Wescott

    Tim Wescott Guest

    You keep distracting me when I'm supposed to be working! Can't you ask
    questions about _boring_ things, or things that I don't know the answers to,
    fer cryin out loud?

    Try the MC145170-2 (this must be why Motorola is spinning off their
    semiconductor division -- the part numbers are getting too long). It's not
    the one that I've used but it looks good on paper. You will have to program
    it serially; they don't have a parallel load one that'll go over 20MHz.

  4. John Larkin

    John Larkin Guest


  5. Genome

    Genome Guest

    "If all else fails...."


    You mean all those other dribbly posts about op-amps as bandpass filters and
    varactors and ceramic resonators and pulling them to 8.1-8.2MHz and
    inverting buffers and crap know what else boils down to.....

    "I want to generate 40.5-41MHz in 10KHz steps"


    "May have to implement this project"



    From CMOS gate oscillator to programmable PLL or DDS frequency synthesis in
    one giant leap.

    Now I know there are those out there who don't look too kindly upon this
    Burridge Baiting. Kindly just shut up. Well, feel free to criticise if you
    want. At least take four steps back and carefully consider what's going on

    Be aware, be very aware. Paul Burridge is wasting your time.

    As a useful analogy consider how you would teach someone the art of farting
    before they have mastered the finer points of taking a shit.

    'OK, try it again'
    'Damn..... Look I thought I told you to empty your bowels first'
    'OK, OK.... let's try the enema first.'

    'OK, try it again.'
    'Oh, I give up.'

    I think it's all quite amusing really.


    Death, it's kind of like nothing.
    It's got to be better than this.
  6. Since you're sober for once, I'll respond....

    Yes, channels will do, as will a continuous sweep. It's not important
    for this application.
    Rubbish. I was playing about with PLLs over 20 years ago. And got 3/4
    of the way through my own design of PCM system before other things
    took priority. I passed my amateur radio examinations (with a double
    distinction) in the early 1980s and spent the rest of the decade
    communicating via CW with the old Warsaw Pact countries on 40m. I
    agree there are large disparities in my knowledge base. An explanation
    is required and it's perfectly simple: I never followed a formalised
    course in electronics at all. What I do know I taught myself on and
    off over a period of years from age 9 and only intently studied the
    bits of the subject I found interesting. Hence there *are* I freely
    admit, fundamental gaps here and there that show up from time to time.
    I'm constantly working on filling in the gaps despite what others may
    think. But the suggestion that I'm trolling is complete rubbish. If
    you don't like reading my postings I suggest you employ your killfile.
    I'm waiting for my main computer to come back so I can make full use
    of *mine* and you'll be one of the first entries in it.

    I'll close by giving everyone a chance to read once again the type of
    crap *you* typically post here and leave them to decide which of us is
    wasting bandwidth:
  7. Active8

    Active8 Guest

    Isn't that the Limey R/C band where you get to butt f*#k each other
    on adjacent channels rather than share the band with (read "take it
    up the butt from") paging services, etc. like we Yanks do?

    which is also covered in AN1207. General design note is AN535. If
    you like, we can quiz you before you quiz us. That way we can act
    rather than react.

    Prerequisites / stuff to know:

    Complex numbers
    Electronic Circuit Analysis
    Diff eq.
    Laplace transforms
    Feedback and Control Theory

    Understand poles and zeros and pole zero analysis.
    Understand Bode plots.
    Understand Nyquist Stability.

    What'd I leave out? -- MCU's...

    Suggested reading:

    Everything, everything else, everything related that's archived at
    Google, and the bit on how to pronounce "Bode".

    Alternate Approach I - The Psuedoscientific Approach:

    Finding and Hiring a Consultant.
    Raising Capital to Pay Consultant.
    Writing a Business Plan to Connive $ Out of VC.
    Talking Shit to VC's.
    How to Find a VC That Doesn't Know F' All
    About Electronics but Has Too Much Money and Too Few Smarts.
    Getting More Money Out of VC to Pay More Consultant Fees.
    Promising Shares in a Nonexistant Company.
    Jumping Ship and Skipping Town When VC Stops Sending Checks.
    Obfuscation of the Business Entity, Litigation, and How the Appeal
    Process Works Against the Plaintiff. - from the law offices of
    Block, Stall, Wild, and Wilder.

    Alternate Approach II - The Green Bean Approach, AKA cheating:

    Hack through it. Find a circuit on inet.

  8. Leon Heller

    Leon Heller Guest

    A DDS is the easiest way to do this. Have a look at the AD9850 and
    friends from ADI.

  9. Active8

    Active8 Guest

    Did I also read something to the effect that it could be swept?
    Maybe if you tell us what yer up to, we can suggest something.
    PCM with a PLL? You mean PCM data sent thru a PLL controlled Tx?
    Voice of Burridge? ;) And all these years I thought Stealth Tech
    brought down the USSR.

    u will comply. ohms r futile. u will b assimilated. SK
    ohms r futile.
    How old are you, anyway?

  10. Thanks, Leon. I've never heard of it but will do a search and find
    I've also ordered a load of xtals and resonators this morning in the
    expectation I may have to cobble up some combination of
    multiplication, mixing; sum and difference and filtering etc. to get
    what I want. What a nightmare and only a week to go. :-(
  11. Yep, see below.
    It's not rocket science, Mike. Just want to sweep the r/c channels at
    40Mhz to test the effectiveness of some filters I'm going to build to
    protect our robots from interference, that's all. Frank ("RF" Frank)
    was kind enough to send me a design for a sweep generator for 40Mhz
    and it worked great (even with my old-style, hopelessly bad boards
    -must have been a stable design so thanks, Frank). *However* due to
    unforseseen circumstances, we've been limited to using the very top of
    the available band and Frank's design doesn't quite get there. Not his
    fault but *mine* I hasten to add (made careless error with the
    original spec). Anyway, this shift to the top end of the band
    necessitates a re-working of the sweep-gen.
    No, no, no. They were two seperate and unrelated projects. The PCM
    idea was an early attempt of mine to digitise, compress and encrypt
    speech channels.
    Hehe! The poor old Russians back then never really said much at all -
    they weren't allowed to chat in general terms thanks to the cold war
    and all that. But I got a lot of practice on the conversational side
    of CW with the Germans. They're a great bunch of people and very
    friendly. You woudn't think feelings could come across over such a
    monochrome and sterile medium but I can assure you that Morse is much
    <mumble, mumble> Sore point! :-(
  12. none

    none Guest

    perhaps the AD4001.

    Though I might also recommend having a look at a DDS such as
    the AD9854

  13. Active8

    Active8 Guest

    Oh. That's a whole subject.

    While DDS would be easiest for you, I don't think you need that or
    a PLL. Just sweep the osc with a ramp and add markers for your freq

    Anybody remember the easy way to get a marker pip?

    If the output amplitude of the osc is not constant across the band,
    you can use a sweep comparator setup where the direct osc out is
    compared to the filtered output. So if there's no filter (a jumper)
    you get a flat line regardless of amplitude variations.
    Ah. Paisan.

  14. Active8

    Active8 Guest

    Gaff the resonators. You said you were having trouble pulling them
    to the top of the band. Run some varactors in their most linear
    range against a coil. You don't need exact freqs to see the shape
    of the filter.

    I think you can use the crystals to give you those marker pips.
    They'll peak as the osc sweeps through their freqs. Jusr don't over
    drive 'em.

    Look up sweep generator and sweep comparator. save a boatload of
  15. Fred Bloggs

    Fred Bloggs Guest

    PLONK him and his threads.
  16. Excellent advice! I plan to do exactly the same with you and your
    colleague just as soon as I get my full version of Agent back.
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