On 10/16/2012 11:56 AM, Jim Thompson wrote:> On Tue, 16 Oct 2012 11:25:52 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> On 10/15/2012 07:59 PM, Jim Thompson wrote: >>> Finally zeroing in on modeling the 74HC4046 after finding a >>> unpublished AppNote that gave more details on the innards. This is >>> what a fixed frequency looks like, simulation-wise... >>> >>> http://www.analog-innovations.com/SED/HC4046_VCO_2_SIM.pdf >>> >>> Comments? Scalings? (This is based on AppNote and Datasheets >>> claiming trip at VDD/2). >>> >>> First release will be VCO only and will be in LTspice format. Once >>> you approve that, the PFD is virtually all logic. >>> >>> ...Jim Thompson >> >> Different manufacturers give you a wide variety of ridiculously >> nonlinear tuning curves for the VCO--the tuning sensitivity varies like >> 3:1, > > I don't think most users fret over the incremental slope. The > "follower" variation is trivial to fix by adding an OpAmp. Sinking > one end of the capacitor into the substrate diode every half cycle is > something you have to live with if you like 4046's. I'm doing this > for fun (and requests from this group)... I wouldn't use one myself. > Get my MC4024 if you want better linearity. I think there's also a > PECL copy, but I don't remember the part number off the top of my > head. Or use a V-to-F chip. > >> and the oscillator quits below about 0.7-1.1V (@VDD=5) depending on >> the device. > > That's noted on the data sheet. Why does that give you such > heartburn? Do you really need zero frequency? > >> >> Which did you pick? ;) > > I have the most complete data on the TI 'HC4046, but I was aiming sort > of average ;-) since I'm building it from behavioral blocks. > > I would guess that you're one of the few people in the world that > would need a flat-ass accurate fit to one particular version. > >> >> (The metal gate 4046-style oscillators all stink on ice--HC4046, HC7046, >> HC9046, all makers, all horrible. PD2 is nice if you stay out of the >> dead zone.) >> >> Cheers >> >> Phil Hobbs > > What do you really need? An accurate V-to-F? > > ...Jim ThompsonThe loop gain is proportional to K_VCO * K_phi, so if the tuning sensitivity varies all over the map like that, so does the frequency compensation of the loop. That's what makes the HC4046 and its brethren so sucky. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Pinging 74HC4046 Users
Started by ●October 15, 2012
Reply by ●October 16, 20122012-10-16
Reply by ●October 16, 20122012-10-16
On Tue, 16 Oct 2012 14:02:39 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 10/16/2012 11:56 AM, Jim Thompson wrote: >> On Tue, 16 Oct 2012 11:25:52 -0400, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>> On 10/15/2012 07:59 PM, Jim Thompson wrote: >>>> Finally zeroing in on modeling the 74HC4046 after finding a >>>> unpublished AppNote that gave more details on the innards. This is >>>> what a fixed frequency looks like, simulation-wise... >>>> >>>> http://www.analog-innovations.com/SED/HC4046_VCO_2_SIM.pdf >>>> >>>> Comments? Scalings? (This is based on AppNote and Datasheets >>>> claiming trip at VDD/2). >>>> >>>> First release will be VCO only and will be in LTspice format. Once >>>> you approve that, the PFD is virtually all logic. >>>> >>>> ...Jim Thompson >>> >>> Different manufacturers give you a wide variety of ridiculously >>> nonlinear tuning curves for the VCO--the tuning sensitivity varies like >>> 3:1, >> >> I don't think most users fret over the incremental slope. The >> "follower" variation is trivial to fix by adding an OpAmp. Sinking >> one end of the capacitor into the substrate diode every half cycle is >> something you have to live with if you like 4046's. I'm doing this >> for fun (and requests from this group)... I wouldn't use one myself. >> Get my MC4024 if you want better linearity. I think there's also a >> PECL copy, but I don't remember the part number off the top of my >> head. Or use a V-to-F chip. >> >>> and the oscillator quits below about 0.7-1.1V (@VDD=5) depending on >>> the device. >> >> That's noted on the data sheet. Why does that give you such >> heartburn? Do you really need zero frequency? >> >>> >>> Which did you pick? ;) >> >> I have the most complete data on the TI 'HC4046, but I was aiming sort >> of average ;-) since I'm building it from behavioral blocks. >> >> I would guess that you're one of the few people in the world that >> would need a flat-ass accurate fit to one particular version. >> >>> >>> (The metal gate 4046-style oscillators all stink on ice--HC4046, HC7046, >>> HC9046, all makers, all horrible. PD2 is nice if you stay out of the >>> dead zone.) >>> >>> Cheers >>> >>> Phil Hobbs >> >> What do you really need? An accurate V-to-F? >> >> ...Jim Thompson > >The loop gain is proportional to K_VCO * K_phi, so if the tuning >sensitivity varies all over the map like that, so does the frequency >compensation of the loop. That's what makes the HC4046 and its brethren >so sucky. > >Cheers > >Phil HobbsI've not even played with one, except to measure some DC. The data sheets would seem to indicate that the non-linearity occurs at the tuning extremes. Just bound your control voltage if you're getting lock-in issues <:-| I don't know why the "designers" of the 4046 didn't do a better job of copying the PECL core of my MC4024 (~1965). All current mode, no diode clamping, etc. ...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.
Reply by ●October 16, 20122012-10-16
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 10/15/2012 07:59 PM, Jim Thompson wrote: >> Finally zeroing in on modeling the 74HC4046 after finding a >> unpublished AppNote that gave more details on the innards. This is >> what a fixed frequency looks like, simulation-wise... >> >> http://www.analog-innovations.com/SED/HC4046_VCO_2_SIM.pdf >> >> Comments? Scalings? (This is based on AppNote and Datasheets >> claiming trip at VDD/2). >> >> First release will be VCO only and will be in LTspice format. Once >> you approve that, the PFD is virtually all logic. >> >> ...Jim Thompson > >Different manufacturers give you a wide variety of ridiculously >nonlinear tuning curves for the VCO--the tuning sensitivity varies like >3:1, and the oscillator quits below about 0.7-1.1V (@VDD=5) depending on >the device.Major deja-vu here :-) I used NXP's MS-DOS tool to cook up some values but they where way off. Fortunately the circuit I tried the HC7046 in is a one-off and not something that needs to go into production. I have used PLLs before but never had so much trouble getting the circuit going. -- Failure does not prove something is impossible, failure simply indicates you are not using the right tools... nico@nctdevpuntnl (punt=.) --------------------------------------------------------------
Reply by ●October 16, 20122012-10-16
On 10/16/2012 02:30 PM, Jim Thompson wrote:> On Tue, 16 Oct 2012 14:02:39 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> On 10/16/2012 11:56 AM, Jim Thompson wrote: >>> On Tue, 16 Oct 2012 11:25:52 -0400, Phil Hobbs >>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>> >>>> On 10/15/2012 07:59 PM, Jim Thompson wrote: >>>>> Finally zeroing in on modeling the 74HC4046 after finding a >>>>> unpublished AppNote that gave more details on the innards. This is >>>>> what a fixed frequency looks like, simulation-wise... >>>>> >>>>> http://www.analog-innovations.com/SED/HC4046_VCO_2_SIM.pdf >>>>> >>>>> Comments? Scalings? (This is based on AppNote and Datasheets >>>>> claiming trip at VDD/2). >>>>> >>>>> First release will be VCO only and will be in LTspice format. Once >>>>> you approve that, the PFD is virtually all logic. >>>>> >>>>> ...Jim Thompson >>>> >>>> Different manufacturers give you a wide variety of ridiculously >>>> nonlinear tuning curves for the VCO--the tuning sensitivity varies like >>>> 3:1, >>> >>> I don't think most users fret over the incremental slope. The >>> "follower" variation is trivial to fix by adding an OpAmp. Sinking >>> one end of the capacitor into the substrate diode every half cycle is >>> something you have to live with if you like 4046's. I'm doing this >>> for fun (and requests from this group)... I wouldn't use one myself. >>> Get my MC4024 if you want better linearity. I think there's also a >>> PECL copy, but I don't remember the part number off the top of my >>> head. Or use a V-to-F chip. >>> >>>> and the oscillator quits below about 0.7-1.1V (@VDD=5) depending on >>>> the device. >>> >>> That's noted on the data sheet. Why does that give you such >>> heartburn? Do you really need zero frequency? >>> >>>> >>>> Which did you pick? ;) >>> >>> I have the most complete data on the TI 'HC4046, but I was aiming sort >>> of average ;-) since I'm building it from behavioral blocks. >>> >>> I would guess that you're one of the few people in the world that >>> would need a flat-ass accurate fit to one particular version. >>> >>>> >>>> (The metal gate 4046-style oscillators all stink on ice--HC4046, HC7046, >>>> HC9046, all makers, all horrible. PD2 is nice if you stay out of the >>>> dead zone.) >>>> >>>> Cheers >>>> >>>> Phil Hobbs >>> >>> What do you really need? An accurate V-to-F? >>> >>> ...Jim Thompson >> >> The loop gain is proportional to K_VCO * K_phi, so if the tuning >> sensitivity varies all over the map like that, so does the frequency >> compensation of the loop. That's what makes the HC4046 and its brethren >> so sucky. >> >> Cheers >> >> Phil Hobbs > > I've not even played with one, except to measure some DC. The data > sheets would seem to indicate that the non-linearity occurs at the > tuning extremes. Just bound your control voltage if you're getting > lock-in issues<:-|Just what I need, another opportunity for a little turd-polishing. ;) The HC4046 isn't impossible to use, it's just sucky for no good reason. Since the frequency vs RC spec is so loose, keeping away from the edges is hard even in a narrowband application. You just have to use really tame loop compensation (which is fine for some things).> > I don't know why the "designers" of the 4046 didn't do a better job of > copying the PECL core of my MC4024 (~1965). All current mode, no > diode clamping, etc.Or even the metal gate CD4046. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●October 16, 20122012-10-16
"Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message news:hpCdnao1ebP9XODNnZ2dnUVZ_jOdnZ2d@supernews.com...> On 10/16/2012 02:30 PM, Jim Thompson wrote: >> On Tue, 16 Oct 2012 14:02:39 -0400, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>> On 10/16/2012 11:56 AM, Jim Thompson wrote: >>>> On Tue, 16 Oct 2012 11:25:52 -0400, Phil Hobbs >>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>> >>>>> On 10/15/2012 07:59 PM, Jim Thompson wrote: >>>>>> Finally zeroing in on modeling the 74HC4046 after finding a >>>>>> unpublished AppNote that gave more details on the innards. This is >>>>>> what a fixed frequency looks like, simulation-wise... >>>>>> >>>>>> http://www.analog-innovations.com/SED/HC4046_VCO_2_SIM.pdf >>>>>> >>>>>> Comments? Scalings? (This is based on AppNote and Datasheets >>>>>> claiming trip at VDD/2). >>>>>> >>>>>> First release will be VCO only and will be in LTspice format. Once >>>>>> you approve that, the PFD is virtually all logic. >>>>>> >>>>>> ...Jim Thompson >>>>> >>>>> Different manufacturers give you a wide variety of ridiculously >>>>> nonlinear tuning curves for the VCO--the tuning sensitivity varies >>>>> like >>>>> 3:1, >>>> >>>> I don't think most users fret over the incremental slope. The >>>> "follower" variation is trivial to fix by adding an OpAmp. Sinking >>>> one end of the capacitor into the substrate diode every half cycle is >>>> something you have to live with if you like 4046's. I'm doing this >>>> for fun (and requests from this group)... I wouldn't use one myself. >>>> Get my MC4024 if you want better linearity. I think there's also a >>>> PECL copy, but I don't remember the part number off the top of my >>>> head. Or use a V-to-F chip. >>>> >>>>> and the oscillator quits below about 0.7-1.1V (@VDD=5) depending on >>>>> the device. >>>> >>>> That's noted on the data sheet. Why does that give you such >>>> heartburn? Do you really need zero frequency? >>>> >>>>> >>>>> Which did you pick? ;) >>>> >>>> I have the most complete data on the TI 'HC4046, but I was aiming sort >>>> of average ;-) since I'm building it from behavioral blocks. >>>> >>>> I would guess that you're one of the few people in the world that >>>> would need a flat-ass accurate fit to one particular version. >>>> >>>>> >>>>> (The metal gate 4046-style oscillators all stink on ice--HC4046, >>>>> HC7046, >>>>> HC9046, all makers, all horrible. PD2 is nice if you stay out of the >>>>> dead zone.) >>>>> >>>>> Cheers >>>>> >>>>> Phil Hobbs >>>> >>>> What do you really need? An accurate V-to-F? >>>> >>>> ...Jim Thompson >>> >>> The loop gain is proportional to K_VCO * K_phi, so if the tuning >>> sensitivity varies all over the map like that, so does the frequency >>> compensation of the loop. That's what makes the HC4046 and its brethren >>> so sucky. >>> >>> Cheers >>> >>> Phil Hobbs >> >> I've not even played with one, except to measure some DC. The data >> sheets would seem to indicate that the non-linearity occurs at the >> tuning extremes. Just bound your control voltage if you're getting >> lock-in issues<:-| > > Just what I need, another opportunity for a little turd-polishing. ;) > > The HC4046 isn't impossible to use, it's just sucky for no good reason. > Since the frequency vs RC spec is so loose, keeping away from the edges is > hard even in a narrowband application. You just have to use really tame > loop compensation (which is fine for some things). > >> >> I don't know why the "designers" of the 4046 didn't do a better job of >> copying the PECL core of my MC4024 (~1965). All current mode, no >> diode clamping, etc. > > Or even the metal gate CD4046. >You are supposed to pick up the turd by its clean end. tm
Reply by ●October 16, 20122012-10-16
On 10/16/2012 04:50 PM, tm wrote:> > "Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message > news:hpCdnao1ebP9XODNnZ2dnUVZ_jOdnZ2d@supernews.com... >> On 10/16/2012 02:30 PM, Jim Thompson wrote: >>> On Tue, 16 Oct 2012 14:02:39 -0400, Phil Hobbs >>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>> >>>> On 10/16/2012 11:56 AM, Jim Thompson wrote: >>>>> On Tue, 16 Oct 2012 11:25:52 -0400, Phil Hobbs >>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>> >>>>>> On 10/15/2012 07:59 PM, Jim Thompson wrote: >>>>>>> Finally zeroing in on modeling the 74HC4046 after finding a >>>>>>> unpublished AppNote that gave more details on the innards. This is >>>>>>> what a fixed frequency looks like, simulation-wise... >>>>>>> >>>>>>> http://www.analog-innovations.com/SED/HC4046_VCO_2_SIM.pdf >>>>>>> >>>>>>> Comments? Scalings? (This is based on AppNote and Datasheets >>>>>>> claiming trip at VDD/2). >>>>>>> >>>>>>> First release will be VCO only and will be in LTspice format. Once >>>>>>> you approve that, the PFD is virtually all logic. >>>>>>> >>>>>>> ...Jim Thompson >>>>>> >>>>>> Different manufacturers give you a wide variety of ridiculously >>>>>> nonlinear tuning curves for the VCO--the tuning sensitivity varies >>>>>> like >>>>>> 3:1, >>>>> >>>>> I don't think most users fret over the incremental slope. The >>>>> "follower" variation is trivial to fix by adding an OpAmp. Sinking >>>>> one end of the capacitor into the substrate diode every half cycle is >>>>> something you have to live with if you like 4046's. I'm doing this >>>>> for fun (and requests from this group)... I wouldn't use one myself. >>>>> Get my MC4024 if you want better linearity. I think there's also a >>>>> PECL copy, but I don't remember the part number off the top of my >>>>> head. Or use a V-to-F chip. >>>>> >>>>>> and the oscillator quits below about 0.7-1.1V (@VDD=5) depending on >>>>>> the device. >>>>> >>>>> That's noted on the data sheet. Why does that give you such >>>>> heartburn? Do you really need zero frequency? >>>>> >>>>>> >>>>>> Which did you pick? ;) >>>>> >>>>> I have the most complete data on the TI 'HC4046, but I was aiming sort >>>>> of average ;-) since I'm building it from behavioral blocks. >>>>> >>>>> I would guess that you're one of the few people in the world that >>>>> would need a flat-ass accurate fit to one particular version. >>>>> >>>>>> >>>>>> (The metal gate 4046-style oscillators all stink on ice--HC4046, >>>>>> HC7046, >>>>>> HC9046, all makers, all horrible. PD2 is nice if you stay out of the >>>>>> dead zone.) >>>>>> >>>>>> Cheers >>>>>> >>>>>> Phil Hobbs >>>>> >>>>> What do you really need? An accurate V-to-F? >>>>> >>>>> ...Jim Thompson >>>> >>>> The loop gain is proportional to K_VCO * K_phi, so if the tuning >>>> sensitivity varies all over the map like that, so does the frequency >>>> compensation of the loop. That's what makes the HC4046 and its brethren >>>> so sucky. >>>> >>>> Cheers >>>> >>>> Phil Hobbs >>> >>> I've not even played with one, except to measure some DC. The data >>> sheets would seem to indicate that the non-linearity occurs at the >>> tuning extremes. Just bound your control voltage if you're getting >>> lock-in issues<:-| >> >> Just what I need, another opportunity for a little turd-polishing. ;) >> >> The HC4046 isn't impossible to use, it's just sucky for no good >> reason. Since the frequency vs RC spec is so loose, keeping away from >> the edges is hard even in a narrowband application. You just have to >> use really tame loop compensation (which is fine for some things). >> >>> >>> I don't know why the "designers" of the 4046 didn't do a better job of >>> copying the PECL core of my MC4024 (~1965). All current mode, no >>> diode clamping, etc. >> >> Or even the metal gate CD4046. >> > > You are supposed to pick up the turd by its clean end. > > tm*satori* Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●October 16, 20122012-10-16
On Tue, 16 Oct 2012 10:54:01 -0500, Tim Wescott <tim@seemywebsite.please> wrote:>On Tue, 16 Oct 2012 11:45:09 -0400, Phil Hobbs wrote: > >> On 10/15/2012 09:40 PM, Jim Thompson wrote: >>> On Mon, 15 Oct 2012 21:22:04 -0400, Phil Hobbs >>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>> >>>> On 10/15/2012 9:16 PM, Nico Coesel wrote: >>>>> Jim Thompson<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> >>>>> wrote: >>>>> >>>>>> Finally zeroing in on modeling the 74HC4046 after finding a >>>>>> unpublished AppNote that gave more details on the innards. This is >>>>>> what a fixed frequency looks like, simulation-wise... >>>>>> >>>>>> http://www.analog-innovations.com/SED/HC4046_VCO_2_SIM.pdf >>>>>> >>>>>> Comments? Scalings? (This is based on AppNote and Datasheets >>>>>> claiming trip at VDD/2). >>>>>> >>>>>> First release will be VCO only and will be in LTspice format. Once >>>>>> you approve that, the PFD is virtually all logic. >>>>> >>>>> Funny. I put a HC7046 into a design recently. Unfortunately there are >>>>> no design tools for calculating the loop filter components. So how >>>>> about modeling the HC7046? It is much more interesting because of the >>>>> lock detect output which can be used as a reset. >>>>> >>>> I investigated all the HC versions (HC4046 from several vendors, >>>> HC7046, >>>> HC9046) about a year back, iirc, and their oscillators are all junk >>>> compared with the ancient metal-gate 4046. They're horribly >>>> nonlinear, all in different ways, which makes it really hard to build >>>> a good PLL. What's worse, their oscillators quit when their control >>>> voltages are within a volt or so of ground (the actual threshold for >>>> misbehaviour varies from device to device). >>>> >>>> The 7046 is enough more expensive that I'd be much happier spending >>>> the dough on a better oscillator, and using the back end of a normal >>>> HC4046 >>>>from a good vendor. >>>> >>>> >>>> Cheers >>>> >>>> Phil Hobs >>> >>> It occurs to me that the variable current input quits at about 1*VTH. >>> So you were trying to get to zero frequency ?:-) >>> >>> Add some offset current and it won't quit oscillating. >>> >>> ...Jim Thompson >> >> The metal gate version works over about 1000:1 range, and is very >> respectably linear--a few percent IIRC, which is much better than good >> enough for inside a PLL. It's really quite pretty in a small way. >> >> The HC parts' nonlinearity is all over the map depending on the vendor, >> and that messes up the loop dynamics really badly. Spicing the HC4046 >> oscillator will definitely be "a trap for young players", as Dave Jones >> says. >> >> With the loop gain varying 3:1 with control voltage, and the centre >> frequency being a very poorly controlled function of the RC, you have >> to make HC4046 loops ridiculously overdamped in the normal case to avoid >> loop instability. If you're using lead-lag compensation, you have to >> put the zero a factor of at least 5 below the nominal unity gain cross, >> whereas with a well-behaved VCO, you can put it right at the unity gain >> cross and have 45 degrees' phase margin. >> >> I'd far rather use an OTA integrator/Schmitt trigger oscillator or >> something like that, with the 4046 PDII. >> >> The HC4046 has its uses, but not nearly as many as if it were really a >> faster CD4046. >> >> Cheers >> >> Phil Hobbs > >Oh, I should know -- OTA Integrator? > >I wish someone would take the 3-state phase detector from the 4046 and >put it into a 6-pin SOT and call it TinyLogic or whatever. It would save >ever so much board space.We build something like the charge-pump detector into FPGAs. We use an external dual schottky diode for the pump-up and pump-down blips, to avoid the deadband that tri-state charge pumps tend to create. We can also delta-sigma those outputs to control our VXCO open-loop. The little function generator chips make nice wide-range, low frequency VCOs. Exar, Maxim? -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
Reply by ●October 17, 20122012-10-17
On Oct 17, 1:12=A0pm, John Larkin <jjlar...@highNOTlandTHIStechnologyPART.com> wrote:> On Tue, 16 Oct 2012 10:54:01 -0500, Tim Wescott > > > > <t...@seemywebsite.please> wrote: > >On Tue, 16 Oct 2012 11:45:09 -0400, Phil Hobbs wrote: > > >> On 10/15/2012 09:40 PM, Jim Thompson wrote: > >>> On Mon, 15 Oct 2012 21:22:04 -0400, Phil Hobbs > >>> <pcdhSpamMeSensel...@electrooptical.net> =A0wrote: > > >>>> On 10/15/2012 9:16 PM, Nico Coesel wrote: > >>>>> Jim Thompson<To-Email-Use-The-Envelope-I...@On-My-Web-Site.com> > >>>>> wrote: > > >>>>>> Finally zeroing in on modeling the 74HC4046 after finding a > >>>>>> unpublished AppNote that gave more details on the innards. =A0This=is> >>>>>> what a fixed frequency looks like, simulation-wise... > > >>>>>>http://www.analog-innovations.com/SED/HC4046_VCO_2_SIM.pdf > > >>>>>> Comments? =A0Scalings? =A0(This is based on AppNote and Datasheets > >>>>>> claiming trip at VDD/2). > > >>>>>> First release will be VCO only and will be in LTspice format. =A0O=nce> >>>>>> you approve that, the PFD is virtually all logic. > > >>>>> Funny. I put a HC7046 into a design recently. Unfortunately there a=re> >>>>> no design tools for calculating the loop filter components. So how > >>>>> about modeling the HC7046? It is much more interesting because of t=he> >>>>> lock detect output which can be used as a reset. > > >>>> I investigated all the HC versions (HC4046 from several vendors, > >>>> HC7046, > >>>> HC9046) about a year back, iirc, and their oscillators are all junk > >>>> compared with the ancient metal-gate 4046. =A0They're horribly > >>>> nonlinear, all in different ways, which makes it really hard to buil=d> >>>> a good PLL. What's worse, their oscillators quit when their control > >>>> voltages are within a volt or so of ground (the actual threshold for > >>>> misbehaviour varies from device to device). > > >>>> The 7046 is enough more expensive that I'd be much happier spending > >>>> the dough on a better oscillator, and using the back end of a normal > >>>> HC4046 > >>>>from a good vendor. > > >>>> Cheers > > >>>> Phil Hobs > > >>> It occurs to me that the variable current input quits at about 1*VTH. > >>> So you were trying to get to zero frequency ?:-) > > >>> Add some offset current and it won't quit oscillating. > > >>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 ==A0 =A0 =A0 =A0...Jim Thompson> > >> The metal gate version works over about 1000:1 range, and is very > >> respectably linear--a few percent IIRC, which is much better than good > >> enough for inside a PLL. =A0It's really quite pretty in a small way. > > >> The HC parts' nonlinearity is all over the map depending on the vendor=,> >> and that messes up the loop dynamics really badly. =A0Spicing the HC40=46> >> oscillator will definitely be "a trap for young players", as Dave Jone=s> >> says. > > >> With the loop gain varying 3:1 with control voltage, and the centre > >> frequency being a very poorly controlled function of the RC, =A0you ha=ve> >> to make HC4046 loops ridiculously overdamped in the normal case to avo=id> >> loop instability. =A0If you're using lead-lag compensation, you have t=o> >> put the zero a factor of at least 5 below the nominal unity gain cross=,> >> whereas with a well-behaved VCO, you can put it right at the unity gai=n> >> cross and have 45 degrees' phase margin. > > >> I'd far rather use an OTA integrator/Schmitt trigger oscillator or > >> something like that, with the 4046 PDII. > > >> The HC4046 has its uses, but not nearly as many as if it were really a > >> faster CD4046. > > >> Cheers > > >> Phil Hobbs > > >Oh, I should know -- OTA Integrator? > > >I wish someone would take the 3-state phase detector from the 4046 and > >put it into a 6-pin SOT and call it TinyLogic or whatever. =A0It would s=ave> >ever so much board space. > > We build something like the charge-pump detector into FPGAs. We use an > external dual schottky diode for the pump-up and pump-down blips, to > avoid the deadband that tri-state charge pumps tend to create. We can > also delta-sigma those outputs to control our VXCO open-loop. > > The little function generator chips make nice wide-range, low > frequency VCOs. Exar, Maxim?And there used to be a fairly wide range of chips available that were designed to be very linear VCOs, intended for use as voltage-to- frequency A/D converters. Analog Devices still seems to be in the business http://www.analog.com/en/analog-to-digital-converters/voltage-to-frequency-= converters/products/index.html Phil Hobbs probably should be using the AD650 - though I can't recommend it on the basis of personal expereience -- Bill Sloman, Sydney
Reply by ●October 17, 20122012-10-17
On 10/16/2012 11:33 PM, Bill Sloman wrote:> On Oct 17, 1:12 pm, John Larkin > <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> On Tue, 16 Oct 2012 10:54:01 -0500, Tim Wescott >> >> >> >> <t...@seemywebsite.please> wrote: >>> On Tue, 16 Oct 2012 11:45:09 -0400, Phil Hobbs wrote: >> >>>> On 10/15/2012 09:40 PM, Jim Thompson wrote: >>>>> On Mon, 15 Oct 2012 21:22:04 -0400, Phil Hobbs >>>>> <pcdhSpamMeSensel...@electrooptical.net> wrote: >> >>>>>> On 10/15/2012 9:16 PM, Nico Coesel wrote: >>>>>>> Jim Thompson<To-Email-Use-The-Envelope-I...@On-My-Web-Site.com> >>>>>>> wrote: >> >>>>>>>> Finally zeroing in on modeling the 74HC4046 after finding a >>>>>>>> unpublished AppNote that gave more details on the innards. This is >>>>>>>> what a fixed frequency looks like, simulation-wise... >> >>>>>>>> http://www.analog-innovations.com/SED/HC4046_VCO_2_SIM.pdf >> >>>>>>>> Comments? Scalings? (This is based on AppNote and Datasheets >>>>>>>> claiming trip at VDD/2). >> >>>>>>>> First release will be VCO only and will be in LTspice format. Once >>>>>>>> you approve that, the PFD is virtually all logic. >> >>>>>>> Funny. I put a HC7046 into a design recently. Unfortunately there are >>>>>>> no design tools for calculating the loop filter components. So how >>>>>>> about modeling the HC7046? It is much more interesting because of the >>>>>>> lock detect output which can be used as a reset. >> >>>>>> I investigated all the HC versions (HC4046 from several vendors, >>>>>> HC7046, >>>>>> HC9046) about a year back, iirc, and their oscillators are all junk >>>>>> compared with the ancient metal-gate 4046. They're horribly >>>>>> nonlinear, all in different ways, which makes it really hard to build >>>>>> a good PLL. What's worse, their oscillators quit when their control >>>>>> voltages are within a volt or so of ground (the actual threshold for >>>>>> misbehaviour varies from device to device). >> >>>>>> The 7046 is enough more expensive that I'd be much happier spending >>>>>> the dough on a better oscillator, and using the back end of a normal >>>>>> HC4046 >>>>> >from a good vendor. >> >>>>>> Cheers >> >>>>>> Phil Hobs >> >>>>> It occurs to me that the variable current input quits at about 1*VTH. >>>>> So you were trying to get to zero frequency ?:-) >> >>>>> Add some offset current and it won't quit oscillating. >> >>>>> ...Jim Thompson >> >>>> The metal gate version works over about 1000:1 range, and is very >>>> respectably linear--a few percent IIRC, which is much better than good >>>> enough for inside a PLL. It's really quite pretty in a small way. >> >>>> The HC parts' nonlinearity is all over the map depending on the vendor, >>>> and that messes up the loop dynamics really badly. Spicing the HC4046 >>>> oscillator will definitely be "a trap for young players", as Dave Jones >>>> says. >> >>>> With the loop gain varying 3:1 with control voltage, and the centre >>>> frequency being a very poorly controlled function of the RC, you have >>>> to make HC4046 loops ridiculously overdamped in the normal case to avoid >>>> loop instability. If you're using lead-lag compensation, you have to >>>> put the zero a factor of at least 5 below the nominal unity gain cross, >>>> whereas with a well-behaved VCO, you can put it right at the unity gain >>>> cross and have 45 degrees' phase margin. >> >>>> I'd far rather use an OTA integrator/Schmitt trigger oscillator or >>>> something like that, with the 4046 PDII. >> >>>> The HC4046 has its uses, but not nearly as many as if it were really a >>>> faster CD4046. >> >>>> Cheers >> >>>> Phil Hobbs >> >>> Oh, I should know -- OTA Integrator? >> >>> I wish someone would take the 3-state phase detector from the 4046 and >>> put it into a 6-pin SOT and call it TinyLogic or whatever. It would save >>> ever so much board space. >> >> We build something like the charge-pump detector into FPGAs. We use an >> external dual schottky diode for the pump-up and pump-down blips, to >> avoid the deadband that tri-state charge pumps tend to create. We can >> also delta-sigma those outputs to control our VXCO open-loop. >> >> The little function generator chips make nice wide-range, low >> frequency VCOs. Exar, Maxim? > > And there used to be a fairly wide range of chips available that were > designed to be very linear VCOs, intended for use as voltage-to- > frequency A/D converters. Analog Devices still seems to be in the > business > > http://www.analog.com/en/analog-to-digital-converters/voltage-to-frequency-converters/products/index.html > > Phil Hobbs probably should be using the AD650 - though I can't > recommend it on the basis of personal expereienceFifteen bucks for a 1-MHz V-F converter? Not me, especially not inside a PLL where 1% linearity is way better than good enough. I'd happily use a metal-gate 4046 at frequencies where they work--all you need is a resistor to ground from the PD2 output to pull it off the dead zone. Above a megahertz or so, a current-programmed triangle wave oscillator is good, or else a linearized LC VCO. You can get linearities of better than 10% in varactor-tuned VCOs by putting in a couple of off-stage resonances. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●October 17, 20122012-10-17
On 10/16/2012 09:11 AM, George Herold wrote:> On Oct 15, 7:59 pm, Jim Thompson<To-Email-Use-The-Envelope-I...@On-My- > Web-Site.com> wrote: >> Finally zeroing in on modeling the 74HC4046 after finding a >> unpublished AppNote that gave more details on the innards. This is >> what a fixed frequency looks like, simulation-wise... >> >> http://www.analog-innovations.com/SED/HC4046_VCO_2_SIM.pdf >> >> Comments? Scalings? (This is based on AppNote and Datasheets >> claiming trip at VDD/2). >> >> First release will be VCO only and will be in LTspice format. Once >> you approve that, the PFD is virtually all logic. >> >> ...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 athttp://www.analog-innovations.com| 1962 | >> >> I love to cook with wine. Sometimes I even put it in the food. > > Hi Jim, Phil. Here�s a plot for a 74HC4046 > > http://bayimg.com/kAEhEaAec > > And for different �charging� resistors. > > http://bayimg.com/kAehmaaEC > > The lines were just drawn by eye. > > As Phil says the oscillations stop if the control voltage falls below > ~1Volt. > (I never used the metal can version so don�t know what I�m missing.) >Those aren't too bad looking, but check out the NXP HC7046 datasheet, p. 24 of http://tinyurl.com/c3xgcgq , or the TI one, P. 14 of http://tinyurl.com/cghq2yb . Even the much-ballyhooed HC9046 has the same sorts of worries, see P.24 of http://tinyurl.com/chlkgwv . Many of the typical curves are probably acceptably linear for most PLL uses, but I for one do not get a warm fuzzy feeling about the unit-to-unit repeatability, based on those curves. And check out the actual HC4046--first in a Chinese knockoff, http://tinyurl.com/buvdkby P. 490, then the TI version, P. 14 of http://tinyurl.com/ckz4ezv , and then in the ON semi versions, P. 11 of http://tinyurl.com/cyymxsl . Compare that with the HEF4046 (NXP metal gate version)--check out the VCO linearity error plot on P. 15 of http://tinyurl.com/cl3c7vv . The TI CD4046B claims 0.7% linearity from 2.5V to 7.5V with a 10V supply, http://tinyurl.com/cpd3skg . The HC versions are all over the map. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
