On Wed, 17 Oct 2012 15:08:55 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>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 unpublished AppNote that gave more details on the innards.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 HobbsTurns out that the principal difference between old CD4046 and new 74HC versions is that the current mirrors in the new versions have GAIN: 6x-8x depending on voltage, i.e. channel-length modulation. Apparently their mis-directed aim was higher operating frequency. The result is extraordinarily bad linearity :-( ...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.
Pinging 74HC4046 Users
Started by ●October 15, 2012
Reply by ●October 17, 20122012-10-17
Reply by ●October 17, 20122012-10-17
On 10/17/2012 03:27 PM, Jim Thompson wrote:> On Wed, 17 Oct 2012 15:08:55 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> 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 > > Turns out that the principal difference between old CD4046 and new > 74HC versions is that the current mirrors in the new versions have > GAIN: 6x-8x depending on voltage, i.e. channel-length modulation. > > Apparently their mis-directed aim was higher operating frequency. The > result is extraordinarily bad linearity :-( > > ...Jim ThompsonThat's very interesting. So they didn't just use bigger FETs for the output devices of the mirrors? How did they do it? Cheers Phil "Bipolar" 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 Wed, 17 Oct 2012 15:33:40 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 10/17/2012 03:27 PM, Jim Thompson wrote: >> On Wed, 17 Oct 2012 15:08:55 -0400, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>> 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 >> >> Turns out that the principal difference between old CD4046 and new >> 74HC versions is that the current mirrors in the new versions have >> GAIN: 6x-8x depending on voltage, i.e. channel-length modulation. >> >> Apparently their mis-directed aim was higher operating frequency. The >> result is extraordinarily bad linearity :-( >> >> ...Jim Thompson > >That's very interesting. So they didn't just use bigger FETs for the >output devices of the mirrors? How did they do it? > >Cheers > >Phil "Bipolar" HobbsMost likely bigger FET's... but I'm guessing they used raw device-size scaling, no cascoding (which minimizes channel-length modulation). I don't have any device library information :-( The sad part of all this is how easy it would be to design a much better VCM... not a difficult task at all. Phil, What is your application? If you need linearity, why not just roll your own, given the high-speed comparators that are now available off-the-shelf. ...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 17, 20122012-10-17
On 10/17/2012 03:57 PM, Jim Thompson wrote:> On Wed, 17 Oct 2012 15:33:40 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> On 10/17/2012 03:27 PM, Jim Thompson wrote: >>> On Wed, 17 Oct 2012 15:08:55 -0400, Phil Hobbs >>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>> >>>> 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 >>> >>> Turns out that the principal difference between old CD4046 and new >>> 74HC versions is that the current mirrors in the new versions have >>> GAIN: 6x-8x depending on voltage, i.e. channel-length modulation. >>> >>> Apparently their mis-directed aim was higher operating frequency. The >>> result is extraordinarily bad linearity :-( >>> >>> ...Jim Thompson >> >> That's very interesting. So they didn't just use bigger FETs for the >> output devices of the mirrors? How did they do it? >> >> Cheers >> >> Phil "Bipolar" Hobbs > > Most likely bigger FET's... but I'm guessing they used raw device-size > scaling, no cascoding (which minimizes channel-length modulation). > > I don't have any device library information :-( > > The sad part of all this is how easy it would be to design a much > better VCM... not a difficult task at all. > > Phil, What is your application? If you need linearity, why not just > roll your own, given the high-speed comparators that are now available > off-the-shelf. > > ...Jim ThompsonI'm not using any PLLs at the moment--you asked about the modelling problem, and the badness of the HC4046 oscillator is one of my pet peeves from many years back. Sort of like you and Democrats. ;) I've often done as you suggest--in fact over the years my main use of HC4046es has been as acquisition aids for my real phase detectors, which are generally diode bridges because their noise is so low. Mini Circuits MPD-1s are good medicine. Just now I'm fighting bit rot in an electromagnetic simulator that worked fine up till yesterday, and debugging a little board full of pHEMTs and 0402s. 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 Tue, 16 Oct 2012 16:19:44 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>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 HobbsTry this... http://www.analog-innovations.com/SED/Oscillator_AnotherArchitecture.pdf Note the frequency, ~46MHz, and the current consumption ;-) It is immaculately linear in frequency versus control current. Now I'm yanking your chain just a wee bit, this is on a 0.18um process, but I'll try it on a 5V process and see how it behaves. But would anyone buy it? ...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 17, 20122012-10-17
On Wed, 17 Oct 2012 17:51:09 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 10/17/2012 03:57 PM, Jim Thompson wrote:[snip]>> >> Phil, What is your application? If you need linearity, why not just >> roll your own, given the high-speed comparators that are now available >> off-the-shelf. >> >> ...Jim Thompson > >I'm not using any PLLs at the moment--you asked about the modelling >problem, and the badness of the HC4046 oscillator is one of my pet >peeves from many years back. Sort of like you and Democrats. ;) > >I've often done as you suggest--in fact over the years my main use of >HC4046es has been as acquisition aids for my real phase detectors, which >are generally diode bridges because their noise is so low. Mini >Circuits MPD-1s are good medicine. > >Just now I'm fighting bit rot in an electromagnetic simulator that >worked fine up till yesterday, and debugging a little board full of >pHEMTs and 0402s. > >Cheers > >Phil HobbsIs it bit rot or root rot ?:-) Don't you love "worked fine up till yesterday" situations? One of my worst pranks was on a young engineer (EE, at OmniComp/GenRad)... he's fretting over a breadboard that "was working yesterday". He goes to lunch and I sit down at the bench with my OptiVisors... http://www.analog-innovations.com/SED/OptiVisorMonster.jpg and spot a solder bridge. I solder suck it up, and the breadboard works. When young engineer returns from lunch he's bewildered and pacing around, then testing, then pacing, then testing... To this day I've never told him... and it's been 27 years ;-) ...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 17, 20122012-10-17
Jim Thompson wrote:> > On Tue, 16 Oct 2012 16:19:44 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > > >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 > > Try this... > > http://www.analog-innovations.com/SED/Oscillator_AnotherArchitecture.pdf > > Note the frequency, ~46MHz, and the current consumption ;-) > > It is immaculately linear in frequency versus control current. > > Now I'm yanking your chain just a wee bit, this is on a 0.18um > process, but I'll try it on a 5V process and see how it behaves. > > But would anyone buy it?As long as it was less than a buck or thereabouts, probably so. Of course the much-maligned Younger Generation might not understand. ;) Cheers Phil Hobbs
Reply by ●October 17, 20122012-10-17
Jim Thompson wrote:> > On Wed, 17 Oct 2012 17:51:09 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > > >On 10/17/2012 03:57 PM, Jim Thompson wrote: > [snip] > >> > >> Phil, What is your application? If you need linearity, why not just > >> roll your own, given the high-speed comparators that are now available > >> off-the-shelf. > >> > >> ...Jim Thompson > > > >I'm not using any PLLs at the moment--you asked about the modelling > >problem, and the badness of the HC4046 oscillator is one of my pet > >peeves from many years back. Sort of like you and Democrats. ;) > > > >I've often done as you suggest--in fact over the years my main use of > >HC4046es has been as acquisition aids for my real phase detectors, which > >are generally diode bridges because their noise is so low. Mini > >Circuits MPD-1s are good medicine. > > > >Just now I'm fighting bit rot in an electromagnetic simulator that > >worked fine up till yesterday, and debugging a little board full of > >pHEMTs and 0402s. > > > >Cheers > > > >Phil Hobbs > > Is it bit rot or root rot ?:-) > > Don't you love "worked fine up till yesterday" situations?Not really. This one's a genuine mystery at the moment--same executable, same input files, last week it ran fine, today it produces hundreds of megabytes of NaN's. Like I said, it's obviously bit rot.> > One of my worst pranks was on a young engineer (EE, at > OmniComp/GenRad)... he's fretting over a breadboard that "was working > yesterday". He goes to lunch and I sit down at the bench with my > OptiVisors... > > http://www.analog-innovations.com/SED/OptiVisorMonster.jpg > > and spot a solder bridge. I solder suck it up, and the breadboard > works. > > When young engineer returns from lunch he's bewildered and pacing > around, then testing, then pacing, then testing...I'd be very happy if my case of bit rot spontaneously fixed itself like that. I did find that the 0402-ish board had a major goof--somebody stuffed NPNs where PNPs should have been. I wonder if there is a useful class of circuits where you could replace PNPs with NPNs without reversing the power supplies, and have it still work.> > To this day I've never told him... and it's been 27 years ;-)He's probably forgotten all about it. Cheers Phil Hobbs
Reply by ●October 17, 20122012-10-17
On Oct 18, 2:56 am, Phil Hobbs <pcdhSpamMeSensel...@electrooptical.net> wrote:> 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 Wescot > >> <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:<snip>> >>>>> 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. > > >>>> 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. > > >>> 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-freq... > > > Phil Hobbs probably should be using the AD650 - though I can't > > recommend it on the basis of personal expereience > > Fifteen bucks for a 1-MHz V-F converter? Not me, especially not inside > a PLL where 1% linearity is way better than good enough.The point was that these are legacy parts, and correspondingly expensive. The LM331 which offers even better linearity, but only goes to 100kHz, turns out to be still available to, but at $6 each in small quantities. I was rather hoping to provoke a response from somebody who is still using that kind of part.> 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,Sure. A 1GHz gbw op amp could take you quite a way above 1MHz.>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.Messy. I'd be thinking of a digitally controlled Direct Digital Synthesis chip, which would be a lot tidier and would probably have a lower jitter (if you low-pass filtered the synthesised sine wave properly). For a seriously low jitter option, a DDS-like system including an MC100E195 might be interesting - if complicated. Coping with the temperature dependence of the delay through the MC100E195 might require Peltier junction or a self-calibrating scheme if you really wanted to exploit the full capacity of the MC100E195. -- Bill Sloman, Sydney
Reply by ●October 18, 20122012-10-18
On Wed, 17 Oct 2012 15:57:57 -0700, Jim Thompson wrote:> On Tue, 16 Oct 2012 16:19:44 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >>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 > > Try this... > > http://www.analog-innovations.com/SED/Oscillator_AnotherArchitecture.pdf > > Note the frequency, ~46MHz, and the current consumption ;-) > > It is immaculately linear in frequency versus control current. > > Now I'm yanking your chain just a wee bit, this is on a 0.18um process, > but I'll try it on a 5V process and see how it behaves. > > But would anyone buy it?I would have bought it up to about seven years ago. That was the last time I used a '46 (actually a '9046 with its better phase detector). I left the oscillator disabled. These days, for the sorts of things I design, I'm more likely to replace the entire application with something like this: http://www.silabs.com/products/clocksoscillators/clocks/Pages/Any-RateJitterAttenuatingClockMultipliers.aspx Regards, Allan
