On 10/11/2012 3:36 PM, Tim Wescott wrote:> How commonly do you see PLL designs referred to as "type I", "type II", > "type III", etc.? Do the terms make sense to you? > > I'm writing a report; don't want to either baffle with bullshit nor leave > out handy terms... >Take a look at the Fairchild datasheet for the MM74HC4046. It refers to Phase Comparators I, II, and III.
PLL Terminology Question
Started by ●October 11, 2012
Reply by ●October 11, 20122012-10-11
Reply by ●October 11, 20122012-10-11
On Oct 11, 7:27�pm, John S <Soph...@invalid.org> wrote:> On 10/11/2012 3:36 PM, Tim Wescott wrote: > > > How commonly do you see PLL designs referred to as "type I", "type II", > > "type III", etc.? �Do the terms make sense to you? > > > I'm writing a report; don't want to either baffle with bullshit nor leave > > out handy terms... > > Take a look at the Fairchild datasheet for the MM74HC4046. It refers to > Phase Comparators I, II, and III.thats something different.. Tim, I would put the term in and also clarify it....a Type one loop with one implicit integrator (the VCO) and a second order active loop filter ...or whatever the case may be... providing 0 Hz frequency error and TBD degress of phase error etc.. Mark Mark
Reply by ●October 12, 20122012-10-12
On Thu, 11 Oct 2012 22:28:01 +0000, Eric Jacobsen wrote:> On Thu, 11 Oct 2012 16:53:50 -0500, Tim Wescott <tim@seemywebsite.com> > wrote: > >>On Thu, 11 Oct 2012 15:58:33 -0500, Vladimir Vassilevsky wrote: >> >>> "Tim Wescott" <tim@seemywebsite.com> wrote: >>>> How commonly do you see PLL designs referred to as "type I", "type >>>> II", "type III", etc.? Do the terms make sense to you? >>> >>> IMO this terminology is used only in Gardner's book; there is no >>> universal meaning. >>> It is about P, PI, or PII control loop. Remnants of old times, when >>> they used to mix the details of implementation with the type of the >>> transfer function. >> >>It certainly has universal meaning in control systems terms: it's the >>number of integrating stages that are cascaded in the loop, either from >>the compensator or the plant. > > I only encountered this recently when using a very old JPL paper that > was pertinent to a problem we were dealing with. I had to look up the > meaning, and they were using it like you do, to indicate the number of > integrators in the loop. > > Most comm people that are familiar with PLLs would likely be more > comfortable with describing a loop by its order, i.e., first order, > second order, etc., which isn't exactly the same thing but seems to be > the more widely understood terminology in my experience.Dayum. Just to make sure I'm on the right page, is a 1st-order loop one with a single integrator in the loop filter, or one with no integrator in the loop filter (and the VCO supplying the integrator)? -- My liberal friends think I'm a conservative kook. My conservative friends think I'm a liberal kook. Why am I not happy that they have found common ground? Tim Wescott, Communications, Control, Circuits & Software http://www.wescottdesign.com
Reply by ●October 12, 20122012-10-12
On Thu, 11 Oct 2012 17:53:55 -0700, Mark wrote:> On Oct 11, 7:27 pm, John S <Soph...@invalid.org> wrote: >> On 10/11/2012 3:36 PM, Tim Wescott wrote: >> >> > How commonly do you see PLL designs referred to as "type I", "type >> > II", "type III", etc.? Do the terms make sense to you? >> >> > I'm writing a report; don't want to either baffle with bullshit nor >> > leave out handy terms... >> >> Take a look at the Fairchild datasheet for the MM74HC4046. It refers to >> Phase Comparators I, II, and III. > > thats something different.. > > Tim, I would put the term in and also clarify it....a Type one loop with > one implicit integrator (the VCO) and a second order active loop filter > ...or whatever the case may be... providing 0 Hz frequency error and > TBD degress of phase error etc..That's what I did. If the customer wants revisions I may look up the meaning of "order" in a PLL and put that in there. It'll be run by some PLL experts; I was specifically brought in to look at their problem with a fresh eye, which means that I may not get all the terms exactly right. -- My liberal friends think I'm a conservative kook. My conservative friends think I'm a liberal kook. Why am I not happy that they have found common ground? Tim Wescott, Communications, Control, Circuits & Software http://www.wescottdesign.com
Reply by ●October 12, 20122012-10-12
Vladimir Vassilevsky wrote:> "Tim Wescott"<tim@seemywebsite.com> wrote: >> How commonly do you see PLL designs referred to as "type I", "type II", >> "type III", etc.? Do the terms make sense to you? > > IMO this terminology is used only in Gardner's book; there is no universal > meaning. > It is about P, PI, or PII control loop. Remnants of old times, when they > used to mix the details of implementation > with the type of the transfer function. > >> I'm writing a report; don't want to either baffle with bullshit nor leave >> out handy terms... > > Since nobody is going to read it anyway, why would that matter? > > Vladimir Vassilevsky > DSP and Mixed Signal Consultant > www.abvolt.com > >Do not know but my wild uneducated guess is that "P" stands for regular feedback as in a standard op-amp circuit, "PI" stands for first derivative (eg: "P dot") and "PII" stands for second derivative (eg: "P double dot").
Reply by ●October 12, 20122012-10-12
On 2012-10-12 11:04, Robert Baer wrote:> Vladimir Vassilevsky wrote: >> "Tim Wescott"<tim@seemywebsite.com> wrote: >>> How commonly do you see PLL designs referred to as "type I", "type II", >>> "type III", etc.? Do the terms make sense to you? >> >> IMO this terminology is used only in Gardner's book; there is no >> universal >> meaning. >> It is about P, PI, or PII control loop. Remnants of old times, when they >> used to mix the details of implementation >> with the type of the transfer function. >> >>> I'm writing a report; don't want to either baffle with bullshit nor >>> leave >>> out handy terms... >> >> Since nobody is going to read it anyway, why would that matter? >> >> Vladimir Vassilevsky >> DSP and Mixed Signal Consultant >> www.abvolt.com >> >> > Do not know but my wild uneducated guess is that "P" stands for regular > feedback as in a standard op-amp circuit, "PI" stands for first > derivative (eg: "P dot") and "PII" stands for second derivative (eg: "P > double dot"). > >'I' stands for an Integral term, not a derivative one. I think that PLL designs should be classified by the number of significant poles and zeroes of their transfer functions. This 'type' business only introduces an extra layer of obscurity. Jeroen Belleman
Reply by ●October 12, 20122012-10-12
On Fri, 12 Oct 2012 00:46:36 -0500, Tim Wescott <tim@seemywebsite.com> wrote:>On Thu, 11 Oct 2012 22:28:01 +0000, Eric Jacobsen wrote: > >> On Thu, 11 Oct 2012 16:53:50 -0500, Tim Wescott <tim@seemywebsite.com> >> wrote: >> >>>On Thu, 11 Oct 2012 15:58:33 -0500, Vladimir Vassilevsky wrote: >>> >>>> "Tim Wescott" <tim@seemywebsite.com> wrote: >>>>> How commonly do you see PLL designs referred to as "type I", "type >>>>> II", "type III", etc.? Do the terms make sense to you? >>>> >>>> IMO this terminology is used only in Gardner's book; there is no >>>> universal meaning. >>>> It is about P, PI, or PII control loop. Remnants of old times, when >>>> they used to mix the details of implementation with the type of the >>>> transfer function. >>> >>>It certainly has universal meaning in control systems terms: it's the >>>number of integrating stages that are cascaded in the loop, either from >>>the compensator or the plant. >> >> I only encountered this recently when using a very old JPL paper that >> was pertinent to a problem we were dealing with. I had to look up the >> meaning, and they were using it like you do, to indicate the number of >> integrators in the loop. >> >> Most comm people that are familiar with PLLs would likely be more >> comfortable with describing a loop by its order, i.e., first order, >> second order, etc., which isn't exactly the same thing but seems to be >> the more widely understood terminology in my experience. > >Dayum. Just to make sure I'm on the right page, is a 1st-order loop one >with a single integrator in the loop filter, or one with no integrator in >the loop filter (and the VCO supplying the integrator)?--- http://www.everythingrf.com/Uploads/Content/File/Phase%20Locked%20Loop%20Design%20Fundamentals.pdf Page 3 -- JF
Reply by ●October 12, 20122012-10-12
>On Thu, 11 Oct 2012 16:53:50 -0500, Tim Wescott <tim@seemywebsite.com> >wrote: > >>On Thu, 11 Oct 2012 15:58:33 -0500, Vladimir Vassilevsky wrote: >> >>> "Tim Wescott" <tim@seemywebsite.com> wrote: >>>> How commonly do you see PLL designs referred to as "type I", "typeII",>>>> "type III", etc.? Do the terms make sense to you? >>> >>> IMO this terminology is used only in Gardner's book; there is no >>> universal meaning. >>> It is about P, PI, or PII control loop. Remnants of old times, whenthey>>> used to mix the details of implementation with the type of thetransfer>>> function. >> >>It certainly has universal meaning in control systems terms: it's the >>number of integrating stages that are cascaded in the loop, either from >>the compensator or the plant. > >I only encountered this recently when using a very old JPL paper that >was pertinent to a problem we were dealing with. I had to look up >the meaning, and they were using it like you do, to indicate the >number of integrators in the loop. > >Most comm people that are familiar with PLLs would likely be more >comfortable with describing a loop by its order, i.e., first order, >second order, etc., which isn't exactly the same thing but seems to be >the more widely understood terminology in my experience. > >> >>I had to sweat through it in my undergraduate days, then help undergrads>>sweat through it as a TA getting my Master's degree. >> >>>> I'm writing a report; don't want to either baffle with bullshit nor >>>> leave out handy terms... >>> >>> Since nobody is going to read it anyway, why would that matter? >> >>Pbpbpbpbpbtht. It will become a cult classic among my customer's >>customers, eagerly read and handed down from elder, competent and stately>>engineers to youngsters who are wet behind the ears and trying to make >>their systems match the performance of the existing ones in the field. >> >>-- >>My liberal friends think I'm a conservative kook. >>My conservative friends think I'm a liberal kook. >>Why am I not happy that they have found common ground? >> >>Tim Wescott, Communications, Control, Circuits & Software >>http://www.wescottdesign.com > >Eric Jacobsen >Anchor Hill Communications >www.anchorhill.com >Gardner distinguishes between 'type' and 'order' where 'type' refers to the number of integrators in the loop and order is simply the order of the denominator polynomial in the transfer function. Take a look at section 2.2.2 of his book (3rd edition). These days, particularly with discrete time loops, the order of the denominator polynomial may have little relevence, since other circuitry/code/register delay's etc. inside the loop will add to the loop order but not change the type. I think Gardner's book is the gospel on this subject so I wouldn't have any problem using those terms as standards. -Doug
Reply by ●October 12, 20122012-10-12
Tim Wescott <tim@seemywebsite.com> writes:> How commonly do you see PLL designs referred to as "type I", "type II", > "type III", etc.? Do the terms make sense to you? > > I'm writing a report; don't want to either baffle with bullshit nor leave > out handy terms...Hi Tim, We used to use those terms in the 80s in our antenna control systems at GTE Government Systems. If I remember correctly, the "number" refers to the number of integrators in the loop. I don't think they are used much today. -- Randy Yates Digital Signal Labs http://www.digitalsignallabs.com
Reply by ●October 12, 20122012-10-12
On Fri, 12 Oct 2012 10:39:14 -0400, Randy Yates <yates@digitalsignallabs.com> wrote:>Tim Wescott <tim@seemywebsite.com> writes: > >> How commonly do you see PLL designs referred to as "type I", "type II", >> "type III", etc.? Do the terms make sense to you? >> >> I'm writing a report; don't want to either baffle with bullshit nor leave >> out handy terms... > >Hi Tim, > >We used to use those terms in the 80s in our antenna control systems at >GTE Government Systems. If I remember correctly, the "number" refers to >the number of integrators in the loop. > >I don't think they are used much today.That is correct. From Gardner's 2nd Edition, page 11: "According to servo terminology, the _type_ of a loop is a number equal to the number of perfect integrators within the loop." ...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.
