24Hz to 60Hz PLL?
in [Design]
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From: Phil Hobbs on 18 Feb 2010 12:23 On 2/18/2010 10:51 AM, Jim Thompson wrote: > On Thu, 18 Feb 2010 10:22:36 -0500, "Michael A. Terrell" > <mike.terrell(a)earthlink.net> wrote: > >> >> Jim Thompson wrote: >>> >>> Michael A. Terrell wrote: >>>> >>>> Microdyne was still using a second source version of the MC4044 ten >>>> years ago. We were having trouble getting a good supply, but i couldn't >>>> convince them to switch to the 4046. The 'Engineer' responsible for >>>> supporting older designs insisted it couldn't be used, because it was >>>> too slow. He wouldn't look at the 20 year old drawings, and wouldn't >>>> admit that the PLL only had to lock to a 100 KHz reference. >>> >>> I have no idea who made the 4046 copy originally, but they blundered >>> several features :-( >> >> >> Wasn't that designed by, or for RCA in the early '70s? I know >> someone who worked for RCA at that time, but he was at the fab. > > I think you're right, Michael. "CD"4046 seems to be the very first > moniker. > > I've not actually tried the current 74HC4046 version but, were it done > right, with today's processing, it could be a screamer. > > ...Jim Thompson The PD is okay, though it still has the deadband, but they screwed up the VCO--it craps out at low voltage. No more 100:1 or 1000:1 VCO ranges. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
From: John Larkin on 18 Feb 2010 12:31 On Thu, 18 Feb 2010 12:23:49 -0500, Phil Hobbs <pcdhSpamMeSenseless(a)electrooptical.net> wrote: >On 2/18/2010 10:51 AM, Jim Thompson wrote: >> On Thu, 18 Feb 2010 10:22:36 -0500, "Michael A. Terrell" >> <mike.terrell(a)earthlink.net> wrote: >> >>> >>> Jim Thompson wrote: >>>> >>>> Michael A. Terrell wrote: >>>>> >>>>> Microdyne was still using a second source version of the MC4044 ten >>>>> years ago. We were having trouble getting a good supply, but i couldn't >>>>> convince them to switch to the 4046. The 'Engineer' responsible for >>>>> supporting older designs insisted it couldn't be used, because it was >>>>> too slow. He wouldn't look at the 20 year old drawings, and wouldn't >>>>> admit that the PLL only had to lock to a 100 KHz reference. >>>> >>>> I have no idea who made the 4046 copy originally, but they blundered >>>> several features :-( >>> >>> >>> Wasn't that designed by, or for RCA in the early '70s? I know >>> someone who worked for RCA at that time, but he was at the fab. >> >> I think you're right, Michael. "CD"4046 seems to be the very first >> moniker. >> >> I've not actually tried the current 74HC4046 version but, were it done >> right, with today's processing, it could be a screamer. >> >> ...Jim Thompson > >The PD is okay, though it still has the deadband, but they screwed up >the VCO--it craps out at low voltage. No more 100:1 or 1000:1 VCO ranges. > >Cheers > >Phil Hobbs The HC4046s I've used have about a 7 ns deadband. Annoying. We've done some nice phase/frequency detectors in FPGAs. Rather than try to make the outputs do charge pumping, we bring out separate hard-CMOS UP and DOWN pulses, and use outboard schottky diodes+resistors into the analog stuff. The whole charge pump concept is a tad flakey, in my opinion. I also like single flipflop bang-bang detection for narrowband loops. No deadband, and loop gain is infinite! John
From: Jim Thompson on 18 Feb 2010 12:50 On Thu, 18 Feb 2010 09:31:35 -0800, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Thu, 18 Feb 2010 12:23:49 -0500, Phil Hobbs ><pcdhSpamMeSenseless(a)electrooptical.net> wrote: > >>On 2/18/2010 10:51 AM, Jim Thompson wrote: >>> On Thu, 18 Feb 2010 10:22:36 -0500, "Michael A. Terrell" >>> <mike.terrell(a)earthlink.net> wrote: >>> >>>> >>>> Jim Thompson wrote: >>>>> >>>>> Michael A. Terrell wrote: >>>>>> >>>>>> Microdyne was still using a second source version of the MC4044 ten >>>>>> years ago. We were having trouble getting a good supply, but i couldn't >>>>>> convince them to switch to the 4046. The 'Engineer' responsible for >>>>>> supporting older designs insisted it couldn't be used, because it was >>>>>> too slow. He wouldn't look at the 20 year old drawings, and wouldn't >>>>>> admit that the PLL only had to lock to a 100 KHz reference. >>>>> >>>>> I have no idea who made the 4046 copy originally, but they blundered >>>>> several features :-( >>>> >>>> >>>> Wasn't that designed by, or for RCA in the early '70s? I know >>>> someone who worked for RCA at that time, but he was at the fab. >>> >>> I think you're right, Michael. "CD"4046 seems to be the very first >>> moniker. >>> >>> I've not actually tried the current 74HC4046 version but, were it done >>> right, with today's processing, it could be a screamer. >>> >>> ...Jim Thompson >> >>The PD is okay, though it still has the deadband, but they screwed up >>the VCO--it craps out at low voltage. No more 100:1 or 1000:1 VCO ranges. >> >>Cheers >> >>Phil Hobbs > >The HC4046s I've used have about a 7 ns deadband. Annoying. > >We've done some nice phase/frequency detectors in FPGAs. Rather than >try to make the outputs do charge pumping, we bring out separate >hard-CMOS UP and DOWN pulses, and use outboard schottky >diodes+resistors into the analog stuff. The whole charge pump concept >is a tad flakey, in my opinion. > >I also like single flipflop bang-bang detection for narrowband loops. >No deadband, and loop gain is infinite! > >John > If you implement the "charge pump" current mirrors on-chip, as I regularly do in my ASIC designs, it becomes a non-issue. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
From: Phil Hobbs on 18 Feb 2010 16:41 On 2/18/2010 12:31 PM, John Larkin wrote: > On Thu, 18 Feb 2010 12:23:49 -0500, Phil Hobbs > <pcdhSpamMeSenseless(a)electrooptical.net> wrote: > >> On 2/18/2010 10:51 AM, Jim Thompson wrote: >>> On Thu, 18 Feb 2010 10:22:36 -0500, "Michael A. Terrell" >>> <mike.terrell(a)earthlink.net> wrote: >>> >>>> >>>> Jim Thompson wrote: >>>>> >>>>> Michael A. Terrell wrote: >>>>>> >>>>>> Microdyne was still using a second source version of the MC4044 ten >>>>>> years ago. We were having trouble getting a good supply, but i couldn't >>>>>> convince them to switch to the 4046. The 'Engineer' responsible for >>>>>> supporting older designs insisted it couldn't be used, because it was >>>>>> too slow. He wouldn't look at the 20 year old drawings, and wouldn't >>>>>> admit that the PLL only had to lock to a 100 KHz reference. >>>>> >>>>> I have no idea who made the 4046 copy originally, but they blundered >>>>> several features :-( >>>> >>>> >>>> Wasn't that designed by, or for RCA in the early '70s? I know >>>> someone who worked for RCA at that time, but he was at the fab. >>> >>> I think you're right, Michael. "CD"4046 seems to be the very first >>> moniker. >>> >>> I've not actually tried the current 74HC4046 version but, were it done >>> right, with today's processing, it could be a screamer. >>> >>> ...Jim Thompson >> >> The PD is okay, though it still has the deadband, but they screwed up >> the VCO--it craps out at low voltage. No more 100:1 or 1000:1 VCO ranges. >> >> Cheers >> >> Phil Hobbs > > The HC4046s I've used have about a 7 ns deadband. Annoying. > > We've done some nice phase/frequency detectors in FPGAs. Rather than > try to make the outputs do charge pumping, we bring out separate > hard-CMOS UP and DOWN pulses, and use outboard schottky > diodes+resistors into the analog stuff. The whole charge pump concept > is a tad flakey, in my opinion. It does have the potentially useful feature that the reference ripple goes away when you're exactly in phase. Might be sort of nice to do the +- pulse thing with some minimum width value for both pulses, and use a fast RC lowpass plus an analog switch to get rid of the up-down bumps when you're near lock. Maybe use the lock detector to control the switch--keep it closed when you're out of lock, and open it briefly to get rid of the barump-bump when you're in lock. The problem is always how much extra phase shift you can tolerate inside the loop, and the VCO already contributes 90 degrees, which doesn't help. > > I also like single flipflop bang-bang detection for narrowband loops. > No deadband, and loop gain is infinite! A few nasty metastability issues, though--same as using D-flops for mixers in offset loops. I learned my lesson about that in 1982, when I was an astronomer masquerading as an EE. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
From: MooseFET on 18 Feb 2010 21:54
On Feb 18, 9:31 am, John Larkin <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > On Thu, 18 Feb 2010 12:23:49 -0500, Phil Hobbs > > > > <pcdhSpamMeSensel...(a)electrooptical.net> wrote: > >On 2/18/2010 10:51 AM, Jim Thompson wrote: > >> On Thu, 18 Feb 2010 10:22:36 -0500, "Michael A. Terrell" > >> <mike.terr...(a)earthlink.net> wrote: > > >>> Jim Thompson wrote: > > >>>> Michael A. Terrell wrote: > > >>>>> Microdyne was still using a second source version of the MC4044 ten > >>>>> years ago. We were having trouble getting a good supply, but i couldn't > >>>>> convince them to switch to the 4046. The 'Engineer' responsible for > >>>>> supporting older designs insisted it couldn't be used, because it was > >>>>> too slow. He wouldn't look at the 20 year old drawings, and wouldn't > >>>>> admit that the PLL only had to lock to a 100 KHz reference. > > >>>> I have no idea who made the 4046 copy originally, but they blundered > >>>> several features :-( > > >>> Wasn't that designed by, or for RCA in the early '70s? I know > >>> someone who worked for RCA at that time, but he was at the fab. > > >> I think you're right, Michael. "CD"4046 seems to be the very first > >> moniker. > > >> I've not actually tried the current 74HC4046 version but, were it done > >> right, with today's processing, it could be a screamer. > > >> ...Jim Thompson > > >The PD is okay, though it still has the deadband, but they screwed up > >the VCO--it craps out at low voltage. No more 100:1 or 1000:1 VCO ranges. > > >Cheers > > >Phil Hobbs > > The HC4046s I've used have about a 7 ns deadband. Annoying. > > We've done some nice phase/frequency detectors in FPGAs. Rather than > try to make the outputs do charge pumping, we bring out separate > hard-CMOS UP and DOWN pulses, and use outboard schottky > diodes+resistors into the analog stuff. The whole charge pump concept > is a tad flakey, in my opinion. If you are going for low noise, you really want the added stage of logic clean up that you get by doing the converting to analog outside the chip. > > I also like single flipflop bang-bang detection for narrowband loops. > No deadband, and loop gain is infinite! It really isn't infinite. On the 74HC74 it is less than infinite because the set up time to cause the output to toggle is longer than the setup to cause it to be the same. I don't recall how big the effect is but it is a small nonzero value. Perhaps with a different flip-flop it is greater than infinity and so it averages out. Also a simple tri-state gate that you only enable while the carry out of the counter chain is true works as a nice sort of phase detector. It is a little like a no dead band version of the 2 flip-flop on in that for most of the cycle, the filter capacitor has no current. |