On Wed, 09 Oct 2013 19:44:09 -0700, bloggs.fredbloggs.fred wrote:> On Wednesday, October 9, 2013 7:43:39 PM UTC-4, Jim Thompson wrote: > > See Analog Devices App Note AN-107 Active Feedback Improves Amplifier > Phase Accuracy - James Wong (1987) .-----------------------------------snip--------------------------------- Spot on! Thanks Fred. Now to crank up LT Spice and play around a bit. RichK.
Odd Circuit, OP Amp over OP Amp
Started by ●October 9, 2013
Reply by ●October 10, 20132013-10-10
Reply by ●October 10, 20132013-10-10
On Thursday, October 10, 2013 3:41:33 PM UTC-4, George Herold wrote:> Say would this improve (reduce) the Q-enhancement one sees in State-variable filters? (Or other integrating filter topologies) >Dunno- have never worked with them.
Reply by ●October 10, 20132013-10-10
On Wed, 09 Oct 2013 23:03:49 -0800, Robert Baer wrote:> John Larkin wrote: >> On Wed, 09 Oct 2013 18:23:20 -0700, Jim Thompson >> <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >> >>> On Wed, 09 Oct 2013 18:18:59 -0700, John Larkin >>> <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >>> >>>> On Wed, 9 Oct 2013 19:51:30 +0000 (UTC), "Rich >>>> K."<Mungedto@nowhere.cc> wrote: >>>> >>>>> Why do you think the op. used this topology over the simple circuit >>>>> 1 example? I thank you for your opinions in advance. >>>> >>>> What's the point? >>> >>> Loop-gain-bandwidth improvement. >>> >>> Do try to keep up with the technology. >>> >>> ...Jim Thompson >> >> Why the hell can't you get a killfile to work? >> >> > Don't bug us with YOUR problems.Thanks all. Much food for thought.
Reply by ●October 10, 20132013-10-10
On Thu, 10 Oct 2013 12:41:33 -0700 (PDT), George Herold <gherold@teachspin.com> wrote:>On Wednesday, October 9, 2013 10:44:09 PM UTC-4, bloggs.fred...@gmail.com wrote: >> On Wednesday, October 9, 2013 7:43:39 PM UTC-4, Jim Thompson wrote: >> >> >> >> See Analog Devices App Note AN-107 Active Feedback Improves Amplifier Phase Accuracy - James Wong (1987) . > >Interesting, thanks. (another old trick that I didn't know.) > >Say would this improve (reduce) the Q-enhancement one sees in State-variable filters? (Or other integrating filter topologies) > >George H.The easy way to cure that, AND dissipation factor problems as well... <http://www.analog-innovations.com/SED/StateVariableFilter(P+1).pdf> Discovered that while trying to make very low frequency hybrid filters for Teltone in the early '70's.>> >> > It may be just a scheme to improve _net_ loop-gain-bandwidth-product. >> > I have a paper somewhere on such multi-OpAmp schemes. I'll post when >> > >> > I find it. >> >> > ...Jim Thompson >> > | James E.Thompson | mens | >> > | Analog Innovations | et | >> > | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | >> > | San Tan Valley, AZ 85142 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....Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 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 11, 20132013-10-11
On Thursday, October 10, 2013 8:38:05 PM UTC-4, Jim Thompson wrote:> On Thu, 10 Oct 2013 12:41:33 -0700 (PDT), George Herold > > <gherold@teachspin.com> wrote: > > >On Wednesday, October 9, 2013 10:44:09 PM UTC-4, bloggs.fred...@gmail.com wrote: > >> On Wednesday, October 9, 2013 7:43:39 PM UTC-4, Jim Thompson wrote: >> See Analog Devices App Note AN-107 Active Feedback Improves Amplifier Phase Accuracy - James Wong (1987) . > > > >Interesting, thanks. (another old trick that I didn't know. > > > >Say would this improve (reduce) the Q-enhancement one sees in State-variable filters? (Or other integrating filter topologies) > > > >George H. > The easy way to cure that, AND dissipation factor problems as well... > <http://www.analog-innovations.com/SED/StateVariableFilter(P+1).pdf> >Interesting, Thanks!.. I've never had much of an issue with cap dissipation.. (I just use expensive caps :^) One 'issue' with your circuit is it's got a lot more R's to change if one wants to change the Q or freqeucny. (Hmm can I get a Q higher than 2?) You should write a book with your circuit ideas, implementations. I'd pay a few hundred for it... maybe you can get some cute young thing to help with editing...(as long as the wife doesn't object. :^) George H.> Discovered that while trying to make very low frequency hybrid filters > for Teltone in the early '70's> >> > >> > It may be just a scheme to improve _net_ loop-gain-bandwidth-product. > >> > I have a paper somewhere on such multi-OpAmp schemes. I'll post when > >> > > >> > I find it. > >> > >> > ...Jim Thompson > >> > | James E.Thompson | mens > >> > | Analog Innovations | et | > >> > | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | > >> > | San Tan Valley, AZ 85142 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. > > > > ...Jim Thompson > > -- > > | James E.Thompson | mens | > > | Analog Innovations | et | > > | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | > > | San Tan Valley, AZ 85142 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 11, 20132013-10-11
On Fri, 11 Oct 2013 06:27:20 -0700 (PDT), George Herold <gherold@teachspin.com> wrote:>On Thursday, October 10, 2013 8:38:05 PM UTC-4, Jim Thompson wrote: >> On Thu, 10 Oct 2013 12:41:33 -0700 (PDT), George Herold >> >> <gherold@teachspin.com> wrote: >> >> >On Wednesday, October 9, 2013 10:44:09 PM UTC-4, bloggs.fred...@gmail.com wrote: >> >> On Wednesday, October 9, 2013 7:43:39 PM UTC-4, Jim Thompson wrote: >>> See Analog Devices App Note AN-107 Active Feedback Improves Amplifier Phase Accuracy - James Wong (1987) . >> > >> >Interesting, thanks. (another old trick that I didn't know. >> > >> >Say would this improve (reduce) the Q-enhancement one sees in State-variable filters? (Or other integrating filter topologies) >> > >> >George H. >> The easy way to cure that, AND dissipation factor problems as well... >> <http://www.analog-innovations.com/SED/StateVariableFilter(P+1).pdf> >> >Interesting, Thanks!.. I've never had much of an issue with cap dissipation.. (I just use expensive caps :^) > >One 'issue' with your circuit is it's got a lot more R's to change if one wants to change the Q or freqeucny. (Hmm can I get a Q higher than 2?) > >You should write a book with your circuit ideas, implementations. I'd pay a few hundred for it... maybe you can get some cute young thing to help with editing...(as long as the wife doesn't object. :^) > >George H. > >> Discovered that while trying to make very low frequency hybrid filters >> for Teltone in the early '70's > > >> >> >> >> > It may be just a scheme to improve _net_ loop-gain-bandwidth-product. >> >> > I have a paper somewhere on such multi-OpAmp schemes. I'll post when >> >> > >> >> > I find it. >> >> >> >> > ...Jim Thompson >> >> > | James E.Thompson | mens >> >> > | Analog Innovations | et | >> >> > | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | >> >> > | San Tan Valley, AZ 85142 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.When I was manufacturing those filters, I was making them by the bucket-load, resistors were thick-film, sand-blasted to trim, all automated. An added feature is that you still have one OpAmp available if you are using a quad, so you can easily get a complex zero as well. ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 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 11, 20132013-10-11
>"if you areusing a quad, so you can easily get a complex zero as well. " I wonder why there are so few with three, or five in the package. Why not seven ?
Reply by ●October 11, 20132013-10-11
jurb6006@gmail.com writes:>>"if you are > using a quad, so you can easily get a complex zero as well. " > > I wonder why there are so few with three, or five in the package. Why not seven ?Is it something to do with common centroid design? -- John Devereux
Reply by ●October 11, 20132013-10-11
On Fri, 11 Oct 2013 18:42:12 +0100, John Devereux <john@devereux.me.uk> wrote:>jurb6006@gmail.com writes: > >>>"if you are >> using a quad, so you can easily get a complex zero as well. " >> >> I wonder why there are so few with three, or five in the package. Why not seven ? > >Is it something to do with common centroid design?Pin count and package size. ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 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 11, 20132013-10-11
On Wed, 9 Oct 2013 19:51:30 +0000 (UTC), "Rich K." <Mungedto@nowhere.cc> wrote:>Why do you think the op. used this topology over the simple circuit 1 >example? I thank you for your opinions in advance. > >Attached: LTSpice file. > >------------------------------------------------------------------------ >Version 4 >SHEET 1 880 680 >WIRE 176 -384 48 -384[snip, full listing at Message-ID: <l34c42$ihl$1@dont-email.me>]>TEXT 368 -88 Left 2 ;The designer used this in a 100kz amp. >TEXT 368 -32 Left 2 ;The orignal op amps were TL084'sGetting back to actually looking at it, I'm not sure if it does _anything_ at all. I'll write-out the full-up loop equations and see for sure when I have a free moment ;-) ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 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.
