• spud semi

    From jlarkin@highlandsniptechnology.com@21:1/5 to All on Sat Jul 23 10:03:35 2022
    http://www.potatosemi.com/potatosemiweb/index.html

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Sat Jul 23 13:28:39 2022
    jlarkin@highlandsniptechnology.com wrote:

    http://www.potatosemi.com/potatosemiweb/index.html

    Fun.

    The datasheets all seem to be from 2010, and Octopart doesn't return
    anything for a search on 'PO74'. A pity. I could certainly use a
    noiseless 1.25 GHz HC4046, for instance. (Many extra points for fixing
    the oscillator nonlinearity, some extra points for moving the deadband
    away from the servo point.)

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Gerhard Hoffmann@21:1/5 to All on Sat Jul 23 19:40:59 2022
    Am 23.07.22 um 19:28 schrieb Phil Hobbs:
    jlarkin@highlandsniptechnology.com wrote:

    http://www.potatosemi.com/potatosemiweb/index.html

    Fun.

    The datasheets all seem to be from 2010, and Octopart doesn't return
    anything for a search on 'PO74'.  A pity.  I could certainly use a noiseless 1.25 GHz HC4046, for instance.  (Many extra points for fixing
    the oscillator nonlinearity, some extra points for moving the deadband
    away from the servo point.)

    It seems, the 4096 with it's cleaned-up deadband has died.


    Cheers

    Gerhard

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Gerhard Hoffmann@21:1/5 to All on Sat Jul 23 19:28:18 2022
    Am 23.07.22 um 19:03 schrieb jlarkin@highlandsniptechnology.com:

    http://www.potatosemi.com/potatosemiweb/index.html


    Oh, the first reference to potato semi that is not from
    a high end audio web site, and with ebay as distributor.

    Sorry, no need for inverters that cannot drive 30% of their
    own input capacitance with the delays given.
    (last time I looked, a few years ago)

    Gerhard

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Gerhard Hoffmann on Sat Jul 23 14:55:03 2022
    Gerhard Hoffmann wrote:
    Am 23.07.22 um 19:28 schrieb Phil Hobbs:
    jlarkin@highlandsniptechnology.com wrote:

    http://www.potatosemi.com/potatosemiweb/index.html

    Fun.

    The datasheets all seem to be from 2010, and Octopart doesn't return
    anything for a search on 'PO74'.  A pity.  I could certainly use a
    noiseless 1.25 GHz HC4046, for instance.  (Many extra points for
    fixing the oscillator nonlinearity, some extra points for moving the
    deadband away from the servo point.)

    It seems, the 4096 with it's cleaned-up deadband has died.


    Cheers

    Gerhard

    Yeah, we've gone round the mulberry bush about the 4046's deadband
    several times here in the last decade or so. It's no big deal as long
    as you know the trick--a 1M resistor to ground, just enough to pull the
    servo point a few nanoseconds to one side.

    A 1.25 GHz version would be pretty slick, in a 1980s retro sort of way. ;0

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From boB@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Mon Jul 25 21:34:39 2022
    On Sat, 23 Jul 2022 14:55:03 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Gerhard Hoffmann wrote:
    Am 23.07.22 um 19:28 schrieb Phil Hobbs:
    jlarkin@highlandsniptechnology.com wrote:

    http://www.potatosemi.com/potatosemiweb/index.html

    Fun.

    The datasheets all seem to be from 2010, and Octopart doesn't return
    anything for a search on 'PO74'. A pity. I could certainly use a
    noiseless 1.25 GHz HC4046, for instance. (Many extra points for
    fixing the oscillator nonlinearity, some extra points for moving the
    deadband away from the servo point.)

    It seems, the 4096 with it's cleaned-up deadband has died.


    Cheers

    Gerhard

    Yeah, we've gone round the mulberry bush about the 4046's deadband
    several times here in the last decade or so. It's no big deal as long
    as you know the trick--a 1M resistor to ground, just enough to pull the
    servo point a few nanoseconds to one side.

    A 1.25 GHz version would be pretty slick, in a 1980s retro sort of way. ;0


    Which phase detector do you prefer ?

    boB




    Cheers

    Phil Hobbs

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to boB on Tue Jul 26 08:51:01 2022
    boB wrote:
    On Sat, 23 Jul 2022 14:55:03 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Gerhard Hoffmann wrote:
    Am 23.07.22 um 19:28 schrieb Phil Hobbs:
    jlarkin@highlandsniptechnology.com wrote:

    http://www.potatosemi.com/potatosemiweb/index.html

    Fun.

    The datasheets all seem to be from 2010, and Octopart doesn't return
    anything for a search on 'PO74'.  A pity.  I could certainly use a
    noiseless 1.25 GHz HC4046, for instance.  (Many extra points for
    fixing the oscillator nonlinearity, some extra points for moving the
    deadband away from the servo point.)

    It seems, the 4096 with it's cleaned-up deadband has died.


    Cheers

    Gerhard

    Yeah, we've gone round the mulberry bush about the 4046's deadband
    several times here in the last decade or so. It's no big deal as long
    as you know the trick--a 1M resistor to ground, just enough to pull the
    servo point a few nanoseconds to one side.

    A 1.25 GHz version would be pretty slick, in a 1980s retro sort of way. ;0


    Which phase detector do you prefer ?


    I haven't built an RF PLL in a few years, but at VHF and above I
    normally use a diode ring mixer such as a Mini Circuits MPD-1. Next
    time I want a narrowish-bandwidth loop with very accurate average phase,
    I might try out JL's PECL d-flop trick.

    Cheers

    Phil Hobbs


    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Tue Jul 26 06:49:51 2022
    On Tue, 26 Jul 2022 08:51:01 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    boB wrote:
    On Sat, 23 Jul 2022 14:55:03 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Gerhard Hoffmann wrote:
    Am 23.07.22 um 19:28 schrieb Phil Hobbs:
    jlarkin@highlandsniptechnology.com wrote:

    http://www.potatosemi.com/potatosemiweb/index.html

    Fun.

    The datasheets all seem to be from 2010, and Octopart doesn't return >>>>> anything for a search on 'PO74'. A pity. I could certainly use a
    noiseless 1.25 GHz HC4046, for instance. (Many extra points for
    fixing the oscillator nonlinearity, some extra points for moving the >>>>> deadband away from the servo point.)

    It seems, the 4096 with it's cleaned-up deadband has died.


    Cheers

    Gerhard

    Yeah, we've gone round the mulberry bush about the 4046's deadband
    several times here in the last decade or so. It's no big deal as long
    as you know the trick--a 1M resistor to ground, just enough to pull the
    servo point a few nanoseconds to one side.

    A 1.25 GHz version would be pretty slick, in a 1980s retro sort of way. ;0 >>

    Which phase detector do you prefer ?


    I haven't built an RF PLL in a few years, but at VHF and above I
    normally use a diode ring mixer such as a Mini Circuits MPD-1. Next
    time I want a narrowish-bandwidth loop with very accurate average phase,
    I might try out JL's PECL d-flop trick.

    Cheers

    Phil Hobbs

    What I needed wasn't frequency lock as such, but picosecond time
    alignment of my clock the the OC3 optical data stream.

    Imagine using an XOR or diode mixer to compare my vcxo to an incoming
    square wave. Period is 7 ns, so a +-0.5 volt xor (or mixer) will have
    an error slope of 0.3 volts per ns, 300 uv/ps. Tiny analog errors
    anywhere make picoseconds of time error short term and long term. The
    ecl d-flop has an essentially infinite detector gain, and differential
    ecl is super temperature stable.

    I analyzed the loop assuming that the effective gain was determined by
    jitter and guessed that the detector output would go rail to rail
    differential in 20 ps, once it was lowpass filtered. That was the
    starting point for tweaking, but it was about right. There are a few
    papers out there on infinite-gain pll's but they mostly confused me.

    Simple phase detectors don't find lock if the VCO isn't already close
    to the right frequency, so I used a switchable loop filter, wideband
    to find lock then narrow for low jitter.

    https://www.dropbox.com/s/cobd3t4eorcsgrt/22S880D.pdf?dl=0

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Tue Jul 26 10:41:02 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 26 Jul 2022 08:51:01 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    boB wrote:
    On Sat, 23 Jul 2022 14:55:03 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Gerhard Hoffmann wrote:
    Am 23.07.22 um 19:28 schrieb Phil Hobbs:
    jlarkin@highlandsniptechnology.com wrote:

    http://www.potatosemi.com/potatosemiweb/index.html

    Fun.

    The datasheets all seem to be from 2010, and Octopart doesn't return >>>>>> anything for a search on 'PO74'.  A pity.  I could certainly use a >>>>>> noiseless 1.25 GHz HC4046, for instance.  (Many extra points for
    fixing the oscillator nonlinearity, some extra points for moving the >>>>>> deadband away from the servo point.)

    It seems, the 4096 with it's cleaned-up deadband has died.


    Cheers

    Gerhard

    Yeah, we've gone round the mulberry bush about the 4046's deadband
    several times here in the last decade or so. It's no big deal as long >>>> as you know the trick--a 1M resistor to ground, just enough to pull the >>>> servo point a few nanoseconds to one side.

    A 1.25 GHz version would be pretty slick, in a 1980s retro sort of way. ;0 >>>

    Which phase detector do you prefer ?


    I haven't built an RF PLL in a few years, but at VHF and above I
    normally use a diode ring mixer such as a Mini Circuits MPD-1. Next
    time I want a narrowish-bandwidth loop with very accurate average phase,
    I might try out JL's PECL d-flop trick.


    What I needed wasn't frequency lock as such, but picosecond time
    alignment of my clock the the OC3 optical data stream.

    Imagine using an XOR or diode mixer to compare my vcxo to an incoming
    square wave. Period is 7 ns, so a +-0.5 volt xor (or mixer) will have
    an error slope of 0.3 volts per ns, 300 uv/ps. Tiny analog errors
    anywhere make picoseconds of time error short term and long term. The
    ecl d-flop has an essentially infinite detector gain, and differential
    ecl is super temperature stable.

    Yup, that's pretty compelling. AIUI the loop bandwidth has to be fairly narrow, though, because there's a large-amplitude pseudorandom pulse
    train coming out of the d-flop that you have to get rid of.

    I analyzed the loop assuming that the effective gain was determined by
    jitter and guessed that the detector output would go rail to rail differential in 20 ps, once it was lowpass filtered. That was the
    starting point for tweaking, but it was about right. There are a few
    papers out there on infinite-gain pll's but they mostly confused me.

    Simple phase detectors don't find lock if the VCO isn't already close
    to the right frequency, so I used a switchable loop filter, wideband
    to find lock then narrow for low jitter.

    https://www.dropbox.com/s/cobd3t4eorcsgrt/22S880D.pdf?dl=0



    Yeah, and pull-in is unreliable if the loop filter isn't super simple.

    When the loop is out of lock, the phase detector produces a beat note at
    the difference frequency. The VCO frequency gets pushed slightly higher
    on the positive half cycle of the ripple, and slightly lower on the
    negative half cycle. The half cycle tends to reduce the frequency error
    will get stretched out slightly, and hence the DC component of the beat
    note will not be zero, but will gradually push the loop toward lock.

    With a one-pole loop filter, i.e. a lead-lag integrator, the small
    average DC will push the loop towards lock until it gets within the
    closed-loop bandwidth, at which point it jumps into lock. This mechanism
    is called "pull-in". It tends to be quadratically slow--if your initial
    error is 10x the closed-loop bandwidth, it takes four times longer to
    lock than if it's 5x. (Every acquisition transient is an individual, of course, but the tendency is quadratic.)

    If you put in additional poles to help get rid of the reference
    frequency ripple, they phase shift the reference ripple, so that there
    are beat-frequency regions where the pull-in voltage changes sign,
    tending to push the loop further from lock. Once that starts happening,
    the loop drifts towards the nearest stable null (where the pull-in
    voltage passes through zero). This condition is called "false lock".

    Thus it's usually helpful to add some acquisition aid. One can use a phase-frequency detector, for instance, or (my fave) a triangle sweep
    made out of the loop integrator plus a Schmitt trigger, e.g.

    <https://electrooptical.net/www/sed/PLLSweeper2.asc>.


    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Tue Jul 26 08:06:32 2022
    On Tue, 26 Jul 2022 10:41:02 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 26 Jul 2022 08:51:01 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    boB wrote:
    On Sat, 23 Jul 2022 14:55:03 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Gerhard Hoffmann wrote:
    Am 23.07.22 um 19:28 schrieb Phil Hobbs:
    jlarkin@highlandsniptechnology.com wrote:

    http://www.potatosemi.com/potatosemiweb/index.html

    Fun.

    The datasheets all seem to be from 2010, and Octopart doesn't return >>>>>>> anything for a search on 'PO74'. A pity. I could certainly use a >>>>>>> noiseless 1.25 GHz HC4046, for instance. (Many extra points for >>>>>>> fixing the oscillator nonlinearity, some extra points for moving the >>>>>>> deadband away from the servo point.)

    It seems, the 4096 with it's cleaned-up deadband has died.


    Cheers

    Gerhard

    Yeah, we've gone round the mulberry bush about the 4046's deadband
    several times here in the last decade or so. It's no big deal as long >>>>> as you know the trick--a 1M resistor to ground, just enough to pull the >>>>> servo point a few nanoseconds to one side.

    A 1.25 GHz version would be pretty slick, in a 1980s retro sort of way. ;0


    Which phase detector do you prefer ?


    I haven't built an RF PLL in a few years, but at VHF and above I
    normally use a diode ring mixer such as a Mini Circuits MPD-1. Next
    time I want a narrowish-bandwidth loop with very accurate average phase, >>> I might try out JL's PECL d-flop trick.


    What I needed wasn't frequency lock as such, but picosecond time
    alignment of my clock the the OC3 optical data stream.

    Imagine using an XOR or diode mixer to compare my vcxo to an incoming
    square wave. Period is 7 ns, so a +-0.5 volt xor (or mixer) will have
    an error slope of 0.3 volts per ns, 300 uv/ps. Tiny analog errors
    anywhere make picoseconds of time error short term and long term. The
    ecl d-flop has an essentially infinite detector gain, and differential
    ecl is super temperature stable.

    Yup, that's pretty compelling. AIUI the loop bandwidth has to be fairly >narrow, though, because there's a large-amplitude pseudorandom pulse
    train coming out of the d-flop that you have to get rid of.

    That system sends Manchester data at 77 Mbits/sec. It sends a square
    wave most of the time, with burst of data at about 22 KHz, a couple
    hundred bits. This PLL actually uses the data edges to make lock
    decisions too.

    There are ambiguities so we may have to flip the 77 MHz clock phase
    and try again.



    I analyzed the loop assuming that the effective gain was determined by
    jitter and guessed that the detector output would go rail to rail
    differential in 20 ps, once it was lowpass filtered. That was the
    starting point for tweaking, but it was about right. There are a few
    papers out there on infinite-gain pll's but they mostly confused me.

    Simple phase detectors don't find lock if the VCO isn't already close
    to the right frequency, so I used a switchable loop filter, wideband
    to find lock then narrow for low jitter.

    https://www.dropbox.com/s/cobd3t4eorcsgrt/22S880D.pdf?dl=0



    Yeah, and pull-in is unreliable if the loop filter isn't super simple.

    When the loop is out of lock, the phase detector produces a beat note at
    the difference frequency. The VCO frequency gets pushed slightly higher
    on the positive half cycle of the ripple, and slightly lower on the
    negative half cycle. The half cycle tends to reduce the frequency error
    will get stretched out slightly, and hence the DC component of the beat
    note will not be zero, but will gradually push the loop toward lock.

    The wobble-towards-lock is fun to see, but as the VCO freq is further
    off, the wobble gets weaker and eventually doesn't work.


    With a one-pole loop filter, i.e. a lead-lag integrator, the small
    average DC will push the loop towards lock until it gets within the >closed-loop bandwidth, at which point it jumps into lock. This mechanism
    is called "pull-in". It tends to be quadratically slow--if your initial >error is 10x the closed-loop bandwidth, it takes four times longer to
    lock than if it's 5x. (Every acquisition transient is an individual, of >course, but the tendency is quadratic.)

    If you put in additional poles to help get rid of the reference
    frequency ripple, they phase shift the reference ripple, so that there
    are beat-frequency regions where the pull-in voltage changes sign,
    tending to push the loop further from lock. Once that starts happening,
    the loop drifts towards the nearest stable null (where the pull-in
    voltage passes through zero). This condition is called "false lock".


    With 2 KHz loop bandwidth and a 77 MHz clock, ripple wasn't a problem.
    VCXOs have their own lowpass filters inside, ahead of the varicap,
    typically in the 10s of KHz, often undocumented.


    Thus it's usually helpful to add some acquisition aid. One can use a >phase-frequency detector, for instance, or (my fave) a triangle sweep
    made out of the loop integrator plus a Schmitt trigger, e.g.

    <https://electrooptical.net/www/sed/PLLSweeper2.asc>.


    Cheers

    Phil Hobbs

    All great fun. I had software looking for broken-lock indicators and
    switching the clock phase and the loop filters, which was good enough,
    given a perfect GPS based data stream and a good, expensive VCXO that
    was pretty close to start.

    We've had a couple hundred in the field for about 20 years and they
    have been very good. Too good. I'm trying to convince the user that
    it's time to replace them all, but the dumb things refuse to wear out.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Tue Jul 26 11:16:04 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 26 Jul 2022 10:41:02 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 26 Jul 2022 08:51:01 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    boB wrote:
    On Sat, 23 Jul 2022 14:55:03 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Gerhard Hoffmann wrote:
    Am 23.07.22 um 19:28 schrieb Phil Hobbs:
    jlarkin@highlandsniptechnology.com wrote:

    http://www.potatosemi.com/potatosemiweb/index.html

    Fun.

    The datasheets all seem to be from 2010, and Octopart doesn't return >>>>>>>> anything for a search on 'PO74'.  A pity.  I could certainly use a >>>>>>>> noiseless 1.25 GHz HC4046, for instance.  (Many extra points for >>>>>>>> fixing the oscillator nonlinearity, some extra points for moving the >>>>>>>> deadband away from the servo point.)

    It seems, the 4096 with it's cleaned-up deadband has died.


    Cheers

    Gerhard

    Yeah, we've gone round the mulberry bush about the 4046's deadband >>>>>> several times here in the last decade or so. It's no big deal as long >>>>>> as you know the trick--a 1M resistor to ground, just enough to pull the >>>>>> servo point a few nanoseconds to one side.

    A 1.25 GHz version would be pretty slick, in a 1980s retro sort of way. ;0


    Which phase detector do you prefer ?


    I haven't built an RF PLL in a few years, but at VHF and above I
    normally use a diode ring mixer such as a Mini Circuits MPD-1. Next
    time I want a narrowish-bandwidth loop with very accurate average phase, >>>> I might try out JL's PECL d-flop trick.


    What I needed wasn't frequency lock as such, but picosecond time
    alignment of my clock the the OC3 optical data stream.

    Imagine using an XOR or diode mixer to compare my vcxo to an incoming
    square wave. Period is 7 ns, so a +-0.5 volt xor (or mixer) will have
    an error slope of 0.3 volts per ns, 300 uv/ps. Tiny analog errors
    anywhere make picoseconds of time error short term and long term. The
    ecl d-flop has an essentially infinite detector gain, and differential
    ecl is super temperature stable.

    Yup, that's pretty compelling. AIUI the loop bandwidth has to be fairly
    narrow, though, because there's a large-amplitude pseudorandom pulse
    train coming out of the d-flop that you have to get rid of.

    That system sends Manchester data at 77 Mbits/sec. It sends a square
    wave most of the time, with burst of data at about 22 KHz, a couple
    hundred bits. This PLL actually uses the data edges to make lock
    decisions too.

    There are ambiguities so we may have to flip the 77 MHz clock phase
    and try again.



    I analyzed the loop assuming that the effective gain was determined by
    jitter and guessed that the detector output would go rail to rail
    differential in 20 ps, once it was lowpass filtered. That was the
    starting point for tweaking, but it was about right. There are a few
    papers out there on infinite-gain pll's but they mostly confused me.

    Simple phase detectors don't find lock if the VCO isn't already close
    to the right frequency, so I used a switchable loop filter, wideband
    to find lock then narrow for low jitter.

    https://www.dropbox.com/s/cobd3t4eorcsgrt/22S880D.pdf?dl=0



    Yeah, and pull-in is unreliable if the loop filter isn't super simple.

    When the loop is out of lock, the phase detector produces a beat note at
    the difference frequency. The VCO frequency gets pushed slightly higher
    on the positive half cycle of the ripple, and slightly lower on the
    negative half cycle. The half cycle tends to reduce the frequency error
    will get stretched out slightly, and hence the DC component of the beat
    note will not be zero, but will gradually push the loop toward lock.

    The wobble-towards-lock is fun to see, but as the VCO freq is further
    off, the wobble gets weaker and eventually doesn't work.


    With a one-pole loop filter, i.e. a lead-lag integrator, the small
    average DC will push the loop towards lock until it gets within the
    closed-loop bandwidth, at which point it jumps into lock. This mechanism
    is called "pull-in". It tends to be quadratically slow--if your initial
    error is 10x the closed-loop bandwidth, it takes four times longer to
    lock than if it's 5x. (Every acquisition transient is an individual, of
    course, but the tendency is quadratic.)

    If you put in additional poles to help get rid of the reference
    frequency ripple, they phase shift the reference ripple, so that there
    are beat-frequency regions where the pull-in voltage changes sign,
    tending to push the loop further from lock. Once that starts happening,
    the loop drifts towards the nearest stable null (where the pull-in
    voltage passes through zero). This condition is called "false lock".


    With 2 KHz loop bandwidth and a 77 MHz clock, ripple wasn't a problem.
    VCXOs have their own lowpass filters inside, ahead of the varicap,
    typically in the 10s of KHz, often undocumented.


    Thus it's usually helpful to add some acquisition aid. One can use a
    phase-frequency detector, for instance, or (my fave) a triangle sweep
    made out of the loop integrator plus a Schmitt trigger, e.g.

    <https://electrooptical.net/www/sed/PLLSweeper2.asc>.


    All great fun. I had software looking for broken-lock indicators and switching the clock phase and the loop filters, which was good enough,
    given a perfect GPS based data stream and a good, expensive VCXO that
    was pretty close to start.

    We've had a couple hundred in the field for about 20 years and they
    have been very good. Too good. I'm trying to convince the user that
    it's time to replace them all, but the dumb things refuse to wear out.


    Like old HP laser printers. ;)

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Tue Jul 26 09:20:23 2022
    On Tue, 26 Jul 2022 11:16:04 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 26 Jul 2022 10:41:02 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 26 Jul 2022 08:51:01 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    boB wrote:
    On Sat, 23 Jul 2022 14:55:03 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Gerhard Hoffmann wrote:
    Am 23.07.22 um 19:28 schrieb Phil Hobbs:
    jlarkin@highlandsniptechnology.com wrote:

    http://www.potatosemi.com/potatosemiweb/index.html

    Fun.

    The datasheets all seem to be from 2010, and Octopart doesn't return >>>>>>>>> anything for a search on 'PO74'. A pity. I could certainly use a >>>>>>>>> noiseless 1.25 GHz HC4046, for instance. (Many extra points for >>>>>>>>> fixing the oscillator nonlinearity, some extra points for moving the >>>>>>>>> deadband away from the servo point.)

    It seems, the 4096 with it's cleaned-up deadband has died.


    Cheers

    Gerhard

    Yeah, we've gone round the mulberry bush about the 4046's deadband >>>>>>> several times here in the last decade or so. It's no big deal as long >>>>>>> as you know the trick--a 1M resistor to ground, just enough to pull the >>>>>>> servo point a few nanoseconds to one side.

    A 1.25 GHz version would be pretty slick, in a 1980s retro sort of way. ;0


    Which phase detector do you prefer ?


    I haven't built an RF PLL in a few years, but at VHF and above I
    normally use a diode ring mixer such as a Mini Circuits MPD-1. Next >>>>> time I want a narrowish-bandwidth loop with very accurate average phase, >>>>> I might try out JL's PECL d-flop trick.


    What I needed wasn't frequency lock as such, but picosecond time
    alignment of my clock the the OC3 optical data stream.

    Imagine using an XOR or diode mixer to compare my vcxo to an incoming
    square wave. Period is 7 ns, so a +-0.5 volt xor (or mixer) will have
    an error slope of 0.3 volts per ns, 300 uv/ps. Tiny analog errors
    anywhere make picoseconds of time error short term and long term. The
    ecl d-flop has an essentially infinite detector gain, and differential >>>> ecl is super temperature stable.

    Yup, that's pretty compelling. AIUI the loop bandwidth has to be fairly >>> narrow, though, because there's a large-amplitude pseudorandom pulse
    train coming out of the d-flop that you have to get rid of.

    That system sends Manchester data at 77 Mbits/sec. It sends a square
    wave most of the time, with burst of data at about 22 KHz, a couple
    hundred bits. This PLL actually uses the data edges to make lock
    decisions too.

    There are ambiguities so we may have to flip the 77 MHz clock phase
    and try again.



    I analyzed the loop assuming that the effective gain was determined by >>>> jitter and guessed that the detector output would go rail to rail
    differential in 20 ps, once it was lowpass filtered. That was the
    starting point for tweaking, but it was about right. There are a few
    papers out there on infinite-gain pll's but they mostly confused me.

    Simple phase detectors don't find lock if the VCO isn't already close
    to the right frequency, so I used a switchable loop filter, wideband
    to find lock then narrow for low jitter.

    https://www.dropbox.com/s/cobd3t4eorcsgrt/22S880D.pdf?dl=0



    Yeah, and pull-in is unreliable if the loop filter isn't super simple.

    When the loop is out of lock, the phase detector produces a beat note at >>> the difference frequency. The VCO frequency gets pushed slightly higher >>> on the positive half cycle of the ripple, and slightly lower on the
    negative half cycle. The half cycle tends to reduce the frequency error >>> will get stretched out slightly, and hence the DC component of the beat
    note will not be zero, but will gradually push the loop toward lock.

    The wobble-towards-lock is fun to see, but as the VCO freq is further
    off, the wobble gets weaker and eventually doesn't work.


    With a one-pole loop filter, i.e. a lead-lag integrator, the small
    average DC will push the loop towards lock until it gets within the
    closed-loop bandwidth, at which point it jumps into lock. This mechanism >>> is called "pull-in". It tends to be quadratically slow--if your initial >>> error is 10x the closed-loop bandwidth, it takes four times longer to
    lock than if it's 5x. (Every acquisition transient is an individual, of >>> course, but the tendency is quadratic.)

    If you put in additional poles to help get rid of the reference
    frequency ripple, they phase shift the reference ripple, so that there
    are beat-frequency regions where the pull-in voltage changes sign,
    tending to push the loop further from lock. Once that starts happening, >>> the loop drifts towards the nearest stable null (where the pull-in
    voltage passes through zero). This condition is called "false lock".


    With 2 KHz loop bandwidth and a 77 MHz clock, ripple wasn't a problem.
    VCXOs have their own lowpass filters inside, ahead of the varicap,
    typically in the 10s of KHz, often undocumented.


    Thus it's usually helpful to add some acquisition aid. One can use a
    phase-frequency detector, for instance, or (my fave) a triangle sweep
    made out of the loop integrator plus a Schmitt trigger, e.g.

    <https://electrooptical.net/www/sed/PLLSweeper2.asc>.


    All great fun. I had software looking for broken-lock indicators and
    switching the clock phase and the loop filters, which was good enough,
    given a perfect GPS based data stream and a good, expensive VCXO that
    was pretty close to start.

    We've had a couple hundred in the field for about 20 years and they
    have been very good. Too good. I'm trying to convince the user that
    it's time to replace them all, but the dumb things refuse to wear out.


    Like old HP laser printers. ;)

    Cheers

    Phil Hobbs

    Mine did, and the cartrige prices were absurd anyhow. I got a Brother
    that's great. Refills are big and cheap, and it prints on both sides,
    which I didn't expect from a cheap printer.

    It just sits there quietly. The HP used to power itself up and do a
    cleaning or something noisy in the middle of the night.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Tue Jul 26 14:20:37 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 26 Jul 2022 11:16:04 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 26 Jul 2022 10:41:02 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 26 Jul 2022 08:51:01 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    boB wrote:
    On Sat, 23 Jul 2022 14:55:03 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Gerhard Hoffmann wrote:
    Am 23.07.22 um 19:28 schrieb Phil Hobbs:
    jlarkin@highlandsniptechnology.com wrote:

    http://www.potatosemi.com/potatosemiweb/index.html

    Fun.

    The datasheets all seem to be from 2010, and Octopart doesn't return >>>>>>>>>> anything for a search on 'PO74'.  A pity.  I could certainly use a >>>>>>>>>> noiseless 1.25 GHz HC4046, for instance.  (Many extra points for >>>>>>>>>> fixing the oscillator nonlinearity, some extra points for moving the >>>>>>>>>> deadband away from the servo point.)

    It seems, the 4096 with it's cleaned-up deadband has died.


    Cheers

    Gerhard

    Yeah, we've gone round the mulberry bush about the 4046's deadband >>>>>>>> several times here in the last decade or so. It's no big deal as long >>>>>>>> as you know the trick--a 1M resistor to ground, just enough to pull the
    servo point a few nanoseconds to one side.

    A 1.25 GHz version would be pretty slick, in a 1980s retro sort of way. ;0


    Which phase detector do you prefer ?


    I haven't built an RF PLL in a few years, but at VHF and above I
    normally use a diode ring mixer such as a Mini Circuits MPD-1. Next >>>>>> time I want a narrowish-bandwidth loop with very accurate average phase, >>>>>> I might try out JL's PECL d-flop trick.


    What I needed wasn't frequency lock as such, but picosecond time
    alignment of my clock the the OC3 optical data stream.

    Imagine using an XOR or diode mixer to compare my vcxo to an incoming >>>>> square wave. Period is 7 ns, so a +-0.5 volt xor (or mixer) will have >>>>> an error slope of 0.3 volts per ns, 300 uv/ps. Tiny analog errors
    anywhere make picoseconds of time error short term and long term. The >>>>> ecl d-flop has an essentially infinite detector gain, and differential >>>>> ecl is super temperature stable.

    Yup, that's pretty compelling. AIUI the loop bandwidth has to be fairly >>>> narrow, though, because there's a large-amplitude pseudorandom pulse
    train coming out of the d-flop that you have to get rid of.

    That system sends Manchester data at 77 Mbits/sec. It sends a square
    wave most of the time, with burst of data at about 22 KHz, a couple
    hundred bits. This PLL actually uses the data edges to make lock
    decisions too.

    There are ambiguities so we may have to flip the 77 MHz clock phase
    and try again.



    I analyzed the loop assuming that the effective gain was determined by >>>>> jitter and guessed that the detector output would go rail to rail
    differential in 20 ps, once it was lowpass filtered. That was the
    starting point for tweaking, but it was about right. There are a few >>>>> papers out there on infinite-gain pll's but they mostly confused me. >>>>>
    Simple phase detectors don't find lock if the VCO isn't already close >>>>> to the right frequency, so I used a switchable loop filter, wideband >>>>> to find lock then narrow for low jitter.

    https://www.dropbox.com/s/cobd3t4eorcsgrt/22S880D.pdf?dl=0



    Yeah, and pull-in is unreliable if the loop filter isn't super simple. >>>>
    When the loop is out of lock, the phase detector produces a beat note at >>>> the difference frequency. The VCO frequency gets pushed slightly higher >>>> on the positive half cycle of the ripple, and slightly lower on the
    negative half cycle. The half cycle tends to reduce the frequency error >>>> will get stretched out slightly, and hence the DC component of the beat >>>> note will not be zero, but will gradually push the loop toward lock.

    The wobble-towards-lock is fun to see, but as the VCO freq is further
    off, the wobble gets weaker and eventually doesn't work.


    With a one-pole loop filter, i.e. a lead-lag integrator, the small
    average DC will push the loop towards lock until it gets within the
    closed-loop bandwidth, at which point it jumps into lock. This mechanism >>>> is called "pull-in". It tends to be quadratically slow--if your initial >>>> error is 10x the closed-loop bandwidth, it takes four times longer to
    lock than if it's 5x. (Every acquisition transient is an individual, of >>>> course, but the tendency is quadratic.)

    If you put in additional poles to help get rid of the reference
    frequency ripple, they phase shift the reference ripple, so that there >>>> are beat-frequency regions where the pull-in voltage changes sign,
    tending to push the loop further from lock. Once that starts happening, >>>> the loop drifts towards the nearest stable null (where the pull-in
    voltage passes through zero). This condition is called "false lock".


    With 2 KHz loop bandwidth and a 77 MHz clock, ripple wasn't a problem.
    VCXOs have their own lowpass filters inside, ahead of the varicap,
    typically in the 10s of KHz, often undocumented.


    Thus it's usually helpful to add some acquisition aid. One can use a
    phase-frequency detector, for instance, or (my fave) a triangle sweep
    made out of the loop integrator plus a Schmitt trigger, e.g.

    <https://electrooptical.net/www/sed/PLLSweeper2.asc>.


    All great fun. I had software looking for broken-lock indicators and
    switching the clock phase and the loop filters, which was good enough,
    given a perfect GPS based data stream and a good, expensive VCXO that
    was pretty close to start.

    We've had a couple hundred in the field for about 20 years and they
    have been very good. Too good. I'm trying to convince the user that
    it's time to replace them all, but the dumb things refuse to wear out.


    Like old HP laser printers. ;)

    Cheers

    Phil Hobbs

    Mine did, and the cartrige prices were absurd anyhow. I got a Brother
    that's great. Refills are big and cheap, and it prints on both sides,
    which I didn't expect from a cheap printer.

    It just sits there quietly. The HP used to power itself up and do a
    cleaning or something noisy in the middle of the night.


    We have a LaserJet 2300DTN, which does duplex as well. It's recently
    become a bit hard to get good cartridges for it, so it may have to be
    replaced. :(

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Clifford Heath@21:1/5 to Phil Hobbs on Wed Jul 27 09:52:51 2022
    On 27/7/22 04:20, Phil Hobbs wrote:
    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 26 Jul 2022 11:16:04 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:
    Like old HP laser printers. ;)
    Mine did, and the cartrige prices were absurd anyhow. I got a Brother
    that's great. Refills are big and cheap, and it prints on both sides,
    which I didn't expect from a cheap printer.

    It just sits there quietly. The HP used to power itself up and do a
    cleaning or something noisy in the middle of the night.

    We have a LaserJet 2300DTN, which does duplex as well.  It's recently
    become a bit hard to get good cartridges for it, so it may have to be replaced. :(

    My venerable HP LJ6L only died a couple of years back, after well over a
    decade of service, including many toner transfer PCBs. When I dismantled
    it I found no fewer than eight things broken internally, yet none had
    stopped it from working until the last one.

    The replacement HP P2055dn is nice with the duplexer and all, but it has
    such advanced toner management (turning solid blacks into microscopic cross-hatch patterns) that it's useless for toner transfer, so it's just
    as well the PCB prototyping services are so cheap and quick these days.
    I still miss being able to do a Saturday afternoon turn-around from
    layout to soldering an under an hour though.

    Clifford Heath

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Rich S@21:1/5 to All on Tue Jul 26 18:58:36 2022
    My venerable HP LJ6L only died a couple of years back, after well over a decade of service, including many toner transfer PCBs. When I dismantled
    it I found no fewer than eight things broken internally, yet none had
    stopped it from working until the last one.

    The replacement HP P2055dn is nice with the duplexer and all, but it has
    such advanced toner management (turning solid blacks into microscopic cross-hatch patterns) that it's useless for toner transfer, so it's just
    as well the PCB prototyping services are so cheap and quick these days.
    I still miss being able to do a Saturday afternoon turn-around from
    layout to soldering an under an hour though.

    Clifford Heath

    HI Clifford, Re cross hatch pattern, maybe it is in "toner-saving"
    mode, a.k.a. draft mode. If even "standard" quality has this problem
    then try "high-quality" mode. (I couldn't confirm that this model has
    those quality settings, as strangely, HP does not have any specs
    for it posted on their Support area.)

    In general monochrome lasers from HP & Brother have had the fewest
    reported major problems ('more reliable') than any other brand or type
    of printer. If queried about what printer to buy, always start your recommendations there, friends.
    Regards, Rich S.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Clifford Heath@21:1/5 to Rich S on Thu Jul 28 10:53:54 2022
    On 27/7/22 11:58, Rich S wrote:
    My venerable HP LJ6L only died a couple of years back, after well over a
    decade of service, including many toner transfer PCBs. When I dismantled
    it I found no fewer than eight things broken internally, yet none had
    stopped it from working until the last one.

    The replacement HP P2055dn is nice with the duplexer and all, but it has
    such advanced toner management (turning solid blacks into microscopic
    cross-hatch patterns) that it's useless for toner transfer, so it's just
    as well the PCB prototyping services are so cheap and quick these days.
    I still miss being able to do a Saturday afternoon turn-around from
    layout to soldering an under an hour though.

    Clifford Heath

    HI Clifford, Re cross hatch pattern, maybe it is in "toner-saving"
    mode, a.k.a. draft mode. If even "standard" quality has this problem
    then try "high-quality" mode. (I couldn't confirm that this model has
    those quality settings, as strangely, HP does not have any specs
    for it posted on their Support area.)

    I think I've tried all the settings hat are available to me through
    MacOS CUPS printer subsystem, and through the printer menus. It's
    possible I missed something of course. But "solid" blacks were always
    difficult for laser mechanisms, because to evenly distribute a strong
    static charge (without it repelling itself and causing white blotches)
    is hard. So I think the cross-hatching is a feature of how they handle that.

    I also acquired a HP Color C1518ni (best possible price - I swapped it
    for a homegrown pumpkin!), but only turn it on when I want colour,
    because the cartridges are so expensive.

    In general monochrome lasers from HP & Brother have had the fewest
    reported major problems ('more reliable') than any other brand or type
    of printer. If queried about what printer to buy, always start your recommendations there, friends.

    A lot of folk who've tried toner transfer with Brother lasers say that
    the toner doesn't transfer. I don't know what series or version those
    were, but I didn't want to buy one to find out that it didn't work.

    Clifford Heath.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Dan Purgert@21:1/5 to Clifford Heath on Thu Jul 28 10:07:00 2022
    -----BEGIN PGP SIGNED MESSAGE-----
    Hash: SHA512

    Clifford Heath wrote:
    On 27/7/22 11:58, Rich S wrote:
    [...]
    In general monochrome lasers from HP & Brother have had the fewest
    reported major problems ('more reliable') than any other brand or type
    of printer. If queried about what printer to buy, always start your
    recommendations there, friends.

    A lot of folk who've tried toner transfer with Brother lasers say that
    the toner doesn't transfer. I don't know what series or version those
    were, but I didn't want to buy one to find out that it didn't work.

    I have a Brother 21x0 (70? 80? can't remember, it's still buried under
    moving boxes). It works alright; but in doing research I have found
    that those models (~2004-6) were the start of the "newer(tm)" toners
    that fuse at higher temperatures; which lead to problems for various toner-transfer methods (I've only done the laminator approach).

    Granted, I also don't do toner-transfer all that much, so the errors
    could just as easily be my fault as the toner's.


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    |_|_|O| Github: https://github.com/dpurgert
    |O|O|O| PGP: DDAB 23FB 19FA 7D85 1CC1 E067 6D65 70E5 4CE7 2860

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