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 WIRE 320 -384 240 -384 WIRE 48 -288 48 -384 WIRE 176 -288 48 -288 WIRE 320 -288 320 -384 WIRE 320 -288 256 -288 WIRE 48 -176 48 -288 WIRE 192 -176 48 -176 WIRE 48 -160 48 -176 WIRE 320 -160 320 -288 WIRE 320 -160 256 -160 WIRE 528 -160 320 -160 WIRE 192 -144 112 -144 WIRE 224 -96 224 -128 WIRE 48 -48 48 -80 WIRE 112 48 112 -144 WIRE 112 48 0 48 WIRE 224 64 224 32 WIRE 192 80 176 80 WIRE 352 96 256 96 WIRE 432 96 352 96 WIRE 528 96 432 96 WIRE 0 112 0 48 WIRE 0 112 -160 112 WIRE 192 112 0 112 WIRE 208 112 192 112 WIRE 432 112 432 96 WIRE -160 160 -160 112 WIRE 0 160 0 112 WIRE 224 160 224 128 WIRE 352 176 128 176 WIRE 432 176 352 176 WIRE 352 208 352 176 WIRE 0 272 0 240 WIRE 224 288 224 272 WIRE 176 304 176 80 WIRE 192 304 176 304 WIRE 288 320 256 320 WIRE 128 336 128 176 WIRE 192 336 128 336 WIRE 224 384 224 352 WIRE 176 464 176 304 WIRE 288 464 288 320 WIRE 288 464 256 464 WIRE 176 512 176 464 FLAG 176 592 0 FLAG 352 288 0 FLAG 528 96 out1 FLAG 224 160 -vcc FLAG 224 384 -vcc FLAG 224 32 +vcc FLAG 224 272 +vcc FLAG -96 480 0 FLAG 48 480 0 FLAG 48 400 -vcc FLAG -96 400 +vcc FLAG -160 240 0 FLAG 0 272 0 FLAG 48 -48 0 FLAG 528 -160 out2 FLAG 224 -96 -vcc FLAG 224 -192 +vcc SYMBOL Opamps\\LT1022 224 256 R0 SYMATTR InstName U1 SYMBOL Opamps\\LT1022 224 32 R0 SYMATTR InstName U2 SYMBOL res 336 80 R0 SYMATTR InstName R1 SYMATTR Value 10k SYMBOL res 336 192 R0 SYMATTR InstName R2 SYMATTR Value 1k SYMBOL res 160 496 R0 SYMATTR InstName R4 SYMATTR Value 1k SYMBOL res 272 448 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R5 SYMATTR Value 10k SYMBOL voltage -96 384 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V2 SYMATTR Value 9 SYMBOL voltage 48 496 R180 WINDOW 0 24 96 Left 2 WINDOW 3 24 16 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V1 SYMATTR Value 9 SYMBOL voltage -160 144 R0 WINDOW 3 -118 141 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value SINE(0 0.001 100000) SYMATTR InstName V3 SYMBOL res -16 144 R0 SYMATTR InstName R3 SYMATTR Value 50 SYMBOL cap 416 112 R0 SYMATTR InstName C1 SYMATTR Value 4.7pf SYMBOL Opamps\\LT1022 224 -224 R0 SYMATTR InstName U3 SYMBOL res 272 -304 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R6 SYMATTR Value 10k SYMBOL res 64 -64 R180 WINDOW 0 36 76 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName R7 SYMATTR Value 1k SYMBOL cap 240 -400 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C2 SYMATTR Value 4.7pf TEXT -192 616 Left 2 !.tran 0.001 TEXT 584 -168 Left 2 ;Circuit 1 TEXT 584 96 Left 2 ;Circuit 2 TEXT 368 -88 Left 2 ;The designer used this in a 100kz amp. TEXT 368 -32 Left 2 ;The orignal op amps were TL084's
Odd Circuit, OP Amp over OP Amp
Started by ●October 9, 2013
Reply by ●October 9, 20132013-10-09
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[snip]>TEXT 368 -88 Left 2 ;The designer used this in a 100kz amp. >TEXT 368 -32 Left 2 ;The orignal op amps were TL084'sIt 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.
Reply by ●October 9, 20132013-10-09
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? -- 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 9, 20132013-10-09
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 -- | 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 9, 20132013-10-09
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 ThompsonWhy the hell can't you get a killfile to work? -- 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 9, 20132013-10-09
On Wednesday, October 9, 2013 7:43:39 PM UTC-4, Jim Thompson wrote:>=20 > It may be just a scheme to improve _net_ loop-gain-bandwidth-product. >=20 >=20 >=20 > I have a paper somewhere on such multi-OpAmp schemes. I'll post when >=20 > I find it. >=20 > =09 >=20 > ...Jim Thompson >=20 > --=20 >=20 > | James E.Thompson | mens | >=20 > | Analog Innovations | et | >=20 > | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | >=20 > | San Tan Valley, AZ 85142 Skype: Contacts Only | | >=20 > | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | >=20 > | E-mail Icon at http://www.analog-innovations.com | 1962 | >=20 > =20 >=20 > I love to cook with wine. Sometimes I even put it in the food.We've seen this before, it is a minimal phase passband phase deviation sche= me. Recalling that a phase lag in the feedback network requires a compensat= ing phase lead in the forward amplifier response, the idea is to obtain a f= lat phase response over as much as the passband as possible ( hence the mat= ching OAs with identical gains).
Reply by ●October 9, 20132013-10-09
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) .> 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.
Reply by ●October 10, 20132013-10-10
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.
Reply by ●October 10, 20132013-10-10
On 10/09/2013 10:44 PM, bloggs.fredbloggs.fred@gmail.com wrote:> On Wednesday, October 9, 2013 7:43:39 PM UTC-4, Jim Thompson wrote: > >> 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. > > See Analog Devices App Note AN-107 Active Feedback Improves Amplifier > Phase Accuracy - James Wong (1987) .That's the trick where they used a dual, and put the input of the other op amp in series with the feedback? It was in a PMI app note back around then. I think it also wound up in the OP227 datasheet, or maybe it was the OP270. Cute idea that I've never actually needed to use. 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 10, 20132013-10-10
On Thu, 10 Oct 2013 10:00:40 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 10/09/2013 10:44 PM, bloggs.fredbloggs.fred@gmail.com wrote: >> On Wednesday, October 9, 2013 7:43:39 PM UTC-4, Jim Thompson wrote: >> >>> 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. >> >> See Analog Devices App Note AN-107 Active Feedback Improves Amplifier >> Phase Accuracy - James Wong (1987) . > >That's the trick where they used a dual, and put the input of the other >op amp in series with the feedback? It was in a PMI app note back >around then. I think it also wound up in the OP227 datasheet, or maybe >it was the OP270. > >Cute idea that I've never actually needed to use. > >Cheers > >Phil HobbsSomewhere in my files, now all boxed up for the move :-(, I have an IEEE paper on several configurations that improve effective GBW for integrators. 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.
