Re: [volt-nuts] HP3458 ADC integrator
I eat humble pie - I re-checked the datasheets low limit of 550V/V it is (wow that's really low) David -Original Message- From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of David C. Partridge Sent: 23 February 2018 22:06 To: 'Discussion of precise voltage measurement' Subject: Re: [volt-nuts] HP3458 ADC integrator > The datasheet I have found (Natsemi Sept 1995) lists 550 V/V = 0.55 V/mV. > Which I think is a bit low, but then, the opamp is old. Check other datasheets, that's definitely wrong David ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP3458 ADC integrator
1) Reverse the supplies on U4 (in real circuit reversed supplies will fry the chip.) 2) Add 10k in series with reset switch 3) Swap connections to U4 inputs. 4) Use series shunt switch for reset switch as used in an actual 3458A. Once done together with swapping in LT1220 for LT1225 rest works as expected and output slews due to gate current of J1 and input bias current of U1 Bruce > On 24 February 2018 at 10:23 Attila Kinaliwrote: > > > On Fri, 23 Feb 2018 18:48:24 - > "David C. Partridge" wrote: > > > Looking your schematic, I see that you are using LT1225 for both U2 (U111) > > and U3 (U112) > > > > Why did you use those rather than LM6361 and AD848? Was it just because > > LTSpice didn't have models for them? It can make a difference ... > > Yes. LTSpice doesn't have an LM6361 or AD848. Linear lists the LT1225 > as replacement for LM6361, so I thought this was safe. I deemed the AD848 > to be close enough. > > But as Bruce mentioned, the LT1225 is not unity gain stable, while the > LM6361 is. That might explain the oscillations. > > > BTW LM6361 is 550V/mv not .55V (I assume that was a mistake in your post) > > ... > > Slew rates seem a bit different at +/- 15V supply as well. > > The datasheet I have found (Natsemi Sept 1995) lists 550 V/V = 0.55 V/mV. > Which I think is a bit low, but then, the opamp is old. > > Attila Kinali > -- > It is upon moral qualities that a society is ultimately founded. All > the prosperity and technological sophistication in the world is of no > use without that foundation. > -- Miss Matheson, The Diamond Age, Neil Stephenson > ___ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP3458 ADC integrator
Why do you think that the datasheet is wrong? Its the same as the 1989 version. A lot of the early wideband opamps didn't have high open loop gain. Even the LT1220 only has about 7 - 15x more gain at rated load. The LT1220 has a a pair of cascaded complementary symmetry emitter followers in its output stage compared to the single complementary symmetry emitter follower output stage of the LM6361. Bruce > > On 24 February 2018 at 11:05 "David C. Partridge" >wrote: > > > > > > The datasheet I have found (Natsemi Sept 1995) lists 550 V/V = 0.55 > > V/mV. > > Which I think is a bit low, but then, the opamp is old. > > > > > > Check other datasheets, that's definitely wrong > > David > > ___ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP3458 ADC integrator
> The datasheet I have found (Natsemi Sept 1995) lists 550 V/V = 0.55 V/mV. > Which I think is a bit low, but then, the opamp is old. Check other datasheets, that's definitely wrong David ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP3458 ADC integrator
Attila Some insight can be gleaned by using a single pole model for an opamp configured as an integrator and deriving the expression for the output signal. Look at the non linearity in the output. Look at the voltage at the inverting input. The effective impedance at the inverting input due to feedback action can be modelled as a simple serries network. What are the network parameters? What happens to the non linearity if the positive input is driven in such a way that the inverting input is held at ground? How would one do this? What does the resultant signal at the inverting input look like with real opamps? Whats the maximum GBW of the corrector amp so that the phase margin of the combination isn't reduced too much? ~30 years ago when I first analysed the limitations of opamp analog integrators I didn't have access to Spice and had to resort to Laplace transforms and analytical models of opamps. Bruce > On 24 February 2018 at 10:23 Attila Kinaliwrote: > > > On Fri, 23 Feb 2018 18:48:24 - > "David C. Partridge" wrote: > > > Looking your schematic, I see that you are using LT1225 for both U2 (U111) > > and U3 (U112) > > > > Why did you use those rather than LM6361 and AD848? Was it just because > > LTSpice didn't have models for them? It can make a difference ... > > Yes. LTSpice doesn't have an LM6361 or AD848. Linear lists the LT1225 > as replacement for LM6361, so I thought this was safe. I deemed the AD848 > to be close enough. > > But as Bruce mentioned, the LT1225 is not unity gain stable, while the > LM6361 is. That might explain the oscillations. > > > BTW LM6361 is 550V/mv not .55V (I assume that was a mistake in your post) > > ... > > Slew rates seem a bit different at +/- 15V supply as well. > > The datasheet I have found (Natsemi Sept 1995) lists 550 V/V = 0.55 V/mV. > Which I think is a bit low, but then, the opamp is old. > > Attila Kinali > -- > It is upon moral qualities that a society is ultimately founded. All > the prosperity and technological sophistication in the world is of no > use without that foundation. > -- Miss Matheson, The Diamond Age, Neil Stephenson > ___ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP3458 ADC integrator
On Fri, 23 Feb 2018 18:48:24 - "David C. Partridge"wrote: > Looking your schematic, I see that you are using LT1225 for both U2 (U111) > and U3 (U112) > > Why did you use those rather than LM6361 and AD848? Was it just because > LTSpice didn't have models for them? It can make a difference ... Yes. LTSpice doesn't have an LM6361 or AD848. Linear lists the LT1225 as replacement for LM6361, so I thought this was safe. I deemed the AD848 to be close enough. But as Bruce mentioned, the LT1225 is not unity gain stable, while the LM6361 is. That might explain the oscillations. > BTW LM6361 is 550V/mv not .55V (I assume that was a mistake in your post) ... > Slew rates seem a bit different at +/- 15V supply as well. The datasheet I have found (Natsemi Sept 1995) lists 550 V/V = 0.55 V/mV. Which I think is a bit low, but then, the opamp is old. Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] FW: HP3458 ADC integrator
Good evening! On Fri, 23 Feb 2018 19:02:42 - "David C. Partridge"wrote: > This is a bit time delayed as the attachment was too large, but posting > anyway Ah.. I have the HP3458 schematics, that's where my circuit comes from. Maybe I should have made that more clear. > Take a look at Figure 8 at the bottom of page 12 in the HPJ article. > > U110-U112 in the attached portion of the CLIP just operate (AFAICT) as a > single high gain opamp running open-loop which is shown in Figure 8 as a > single op-amp (the left hand one). U140 to the right is the middle op-amp in > figure 8 and this feeds finally into the comparator (not shown in the > attached). I got this so far. I understand that U110-U112 form an integrator with U111 and U112 added to increase SR and GBW. U110 has been choosen for its low I_bias and V_os TC and provides that to the overall integrato (ie compensates V_os drifft of U111 and U112). Q110 acts as a fast unity gain buffer to isolate U111/U112 from the summing point. U140 acts as a simple amplifier. I included it in my simulations just because it feeds back into the integrator during reset. But I don't understand why the integrator has been done that way. U111 seems redundant when adding U112. It feels like I am missing a key point in what changes in SR and GBW when connecting two opamps. Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP3458 ADC integrator
Hint: start by looking at the summing junction voltage of a single opamp integrator with R = 50k, C = 330pF. NB the LT1225 isnt unity gain stable so its use for any of U2, U3 and U4 is questionable. They will all likely oscillate on their own. Bruce > > On 24 February 2018 at 08:45 Bruce Griffiths> wrote: > > Moin attila > > I'd start with simulating and understanding the integrator in the 34401A, > its a little simpler but still has a coupe of opamps in the integrator. Then > analysing the GBW requirements of the various opamps used in the HP3458A > shoul become somewhat clearer. > > Bruce > > > > > > On 24 February 2018 at 04:51 Attila Kinali wrote: > > > > Moin, > > > > I am trying to understand how the HP 3458 integrator of its > > dual-slope ADC works, as it's a bit more complicated than > > a simple, single opamp integrator. As you can see from the > > attached picture, it consists of 3 opamps (U1-U3) for the > > integrator itself, and another for the slope amplification (U4). > > Unfortunately, I do not get what U2 and U3 are doing, much less > > why they are needed. > > > > So I tried to simulate it in LTspice. But, the circuit oscillates. > > In both, the reset state (when the integration-C shorting switch is > > closed) > > and the integration state (though, less wildly so). I guess, this > > is because I replaced the LM6361 and AD848 by the LT1225 but do not > > understand why, or respectively, which of the differing parameters > > of > > the LT1225 causes this oscillations. > > > > Would someone be so kind and give me some hints? > > > > Thanks in advance > > > > Attila Kinali > > > > -- > > It is upon moral qualities that a society is ultimately founded. All > > the prosperity and technological sophistication in the world is of > > no > > use without that foundation. > > -- Miss Matheson, The Diamond Age, Neil Stephenson > > > > ___ > > volt-nuts mailing list -- volt-nuts@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > > and follow the instructions there. > > > > ___ > > volt-nuts mailing list -- volt-nuts@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > > and follow the instructions there. > > > > > ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP3458 ADC integrator
Moin attila I'd start with simulating and understanding the integrator in the 34401A, its a little simpler but still has a coupe of opamps in the integrator. Then analysing the GBW requirements of the various opamps used in the HP3458A shoul become somewhat clearer. Bruce > > On 24 February 2018 at 04:51 Attila Kinaliwrote: > > Moin, > > I am trying to understand how the HP 3458 integrator of its > dual-slope ADC works, as it's a bit more complicated than > a simple, single opamp integrator. As you can see from the > attached picture, it consists of 3 opamps (U1-U3) for the > integrator itself, and another for the slope amplification (U4). > Unfortunately, I do not get what U2 and U3 are doing, much less > why they are needed. > > So I tried to simulate it in LTspice. But, the circuit oscillates. > In both, the reset state (when the integration-C shorting switch is > closed) > and the integration state (though, less wildly so). I guess, this > is because I replaced the LM6361 and AD848 by the LT1225 but do not > understand why, or respectively, which of the differing parameters of > the LT1225 causes this oscillations. > > Would someone be so kind and give me some hints? > > Thanks in advance > > Attila Kinali > > -- > It is upon moral qualities that a society is ultimately founded. All > the prosperity and technological sophistication in the world is of no > use without that foundation. > -- Miss Matheson, The Diamond Age, Neil Stephenson > > ___ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP3458 ADC integrator
Looking your schematic, I see that you are using LT1225 for both U2 (U111) and U3 (U112) Why did you use those rather than LM6361 and AD848? Was it just because LTSpice didn't have models for them? It can make a difference ... As for why they chose to use 3 op-amps rather than 2? I don't know except that when dealing with low level signals maybe they needed the extra gain. BTW LM6361 is 550V/mv not .55V (I assume that was a mistake in your post) ... Slew rates seem a bit different at +/- 15V supply as well. David -Original Message- From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of Attila Kinali Sent: 23 February 2018 18:02 To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] HP3458 ADC integrator On Fri, 23 Feb 2018 18:31:47 +0100 Attila Kinaliwrote: > And why are U2 and U3 wired up the way they are? Let me expand here a little bit to make it clear what puzzles me. The HP3458 circuit uses 3 opamps: LT1001, LM6361 and AD848. The LT1001 is there for its low input bias current of typ 1.2ns, but has a GBW of typ 0.8MHz, SR of 0.25Vµs and A_vol of 700 V/mV. The LM6361 comes with GBW of 40MHz, SR of 200 V/µs and A_vol of 0.55 V/mV. The AD848 has a GBW of 175MHz, SR of 200 V/µs and A_vol of 13 V/mV. Just by judging from the slew rate, the LM6361 alone should be enough to get the ciruit up to speed, and the AD848 wouldnt be needed. The AD848 has a much higher GBW and A_vol and I can see that both would be beneficial for the integrator. But why not just use a AD848 and leave the LM6361 out? Why use both? The jfet is obviously there to decouple the high speed opamps with their high bias current inputs from the sensitive summing point. C2 is probably to limit the slew rate of U2 in order to keep the integrator stable. But this means that U2+U3 together have some stability problem that could be solved by removing one (preferably U2 as it's the slower of the two). Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP3458 ADC integrator
On Fri, 23 Feb 2018 18:31:47 +0100 Attila Kinaliwrote: > And why are U2 and U3 wired up the way they are? Let me expand here a little bit to make it clear what puzzles me. The HP3458 circuit uses 3 opamps: LT1001, LM6361 and AD848. The LT1001 is there for its low input bias current of typ 1.2ns, but has a GBW of typ 0.8MHz, SR of 0.25Vµs and A_vol of 700 V/mV. The LM6361 comes with GBW of 40MHz, SR of 200 V/µs and A_vol of 0.55 V/mV. The AD848 has a GBW of 175MHz, SR of 200 V/µs and A_vol of 13 V/mV. Just by judging from the slew rate, the LM6361 alone should be enough to get the ciruit up to speed, and the AD848 wouldnt be needed. The AD848 has a much higher GBW and A_vol and I can see that both would be beneficial for the integrator. But why not just use a AD848 and leave the LM6361 out? Why use both? The jfet is obviously there to decouple the high speed opamps with their high bias current inputs from the sensitive summing point. C2 is probably to limit the slew rate of U2 in order to keep the integrator stable. But this means that U2+U3 together have some stability problem that could be solved by removing one (preferably U2 as it's the slower of the two). Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP3458 ADC integrator
On Fri, 23 Feb 2018 17:14:28 - "David C. Partridge"wrote: > The April 1989 HP Journal is mostly dedicated to the 3458A and there's an > article about the dual slope integrator starting on page 8. > > There's also a nice discussion about it in Art of Electronics 3rd Edition > starting on page 918 The HP journal does only mentions a single opamp integrator. The Art of electronics only deals with the close relative used in the HP 34420, which is similar, but not the same. It uses a two opamp structure, which TAoE3 explains to be to increase amplification and slewrate. I guess that can be said about the HP3458 as well, but that begs the question why did they chose a 3 opamp structure? And why are U2 and U3 wired up the way they are? Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP3458 ADC integrator
The April 1989 HP Journal is mostly dedicated to the 3458A and there's an article about the dual slope integrator starting on page 8. There's also a nice discussion about it in Art of Electronics 3rd Edition starting on page 918 HtH David -Original Message- From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of Attila Kinali Sent: 23 February 2018 15:51 To: Discussion of precise voltage measurement Subject: [volt-nuts] HP3458 ADC integrator Moin, I am trying to understand how the HP 3458 integrator of its dual-slope ADC works, as it's a bit more complicated than a simple, single opamp integrator. As you can see from the attached picture, it consists of 3 opamps (U1-U3) for the integrator itself, and another for the slope amplification (U4). Unfortunately, I do not get what U2 and U3 are doing, much less why they are needed. So I tried to simulate it in LTspice. But, the circuit oscillates. In both, the reset state (when the integration-C shorting switch is closed) and the integration state (though, less wildly so). I guess, this is because I replaced the LM6361 and AD848 by the LT1225 but do not understand why, or respectively, which of the differing parameters of the LT1225 causes this oscillations. Would someone be so kind and give me some hints? Thanks in advance Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] HP3458 ADC integrator
Moin, I am trying to understand how the HP 3458 integrator of its dual-slope ADC works, as it's a bit more complicated than a simple, single opamp integrator. As you can see from the attached picture, it consists of 3 opamps (U1-U3) for the integrator itself, and another for the slope amplification (U4). Unfortunately, I do not get what U2 and U3 are doing, much less why they are needed. So I tried to simulate it in LTspice. But, the circuit oscillates. In both, the reset state (when the integration-C shorting switch is closed) and the integration state (though, less wildly so). I guess, this is because I replaced the LM6361 and AD848 by the LT1225 but do not understand why, or respectively, which of the differing parameters of the LT1225 causes this oscillations. Would someone be so kind and give me some hints? Thanks in advance Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson Version 4 SHEET 1 2172 680 WIRE 1936 -416 1840 -416 WIRE 208 -400 96 -400 WIRE 896 -400 208 -400 WIRE 1312 -400 896 -400 WIRE 1792 -400 1392 -400 WIRE 1792 -384 1792 -400 WIRE 1936 -384 1936 -416 WIRE 1840 -368 1840 -416 WIRE -480 -304 -480 -336 WIRE 1840 -304 1840 -320 WIRE 1888 -304 1840 -304 WIRE 1936 -304 1888 -304 WIRE 896 -256 896 -400 WIRE -480 -240 -480 -304 WIRE 352 -224 352 -272 WIRE 896 -192 848 -192 WIRE 944 -192 896 -192 WIRE 96 -160 96 -400 WIRE 304 -160 96 -160 WIRE 848 -144 848 -192 WIRE 944 -128 944 -192 WIRE -480 -112 -480 -160 WIRE -480 -112 -544 -112 WIRE 352 -80 352 -128 WIRE 496 -80 352 -80 WIRE 592 -80 496 -80 WIRE 640 -80 592 -80 WIRE -480 -64 -480 -112 WIRE 720 -48 720 -80 WIRE 640 -32 640 -80 WIRE 688 -32 640 -32 WIRE 1216 -32 1216 -80 WIRE 848 -16 848 -64 WIRE 848 -16 752 -16 WIRE 944 -16 944 -64 WIRE 944 -16 848 -16 WIRE 1008 -16 944 -16 WIRE 1184 -16 1008 -16 WIRE 688 0 624 0 WIRE 1360 0 1248 0 WIRE 1504 0 1360 0 WIRE 1648 0 1504 0 WIRE 1728 0 1648 0 WIRE 1792 0 1792 -304 WIRE 1792 0 1728 0 WIRE 1184 16 1088 16 WIRE 496 48 496 0 WIRE 496 48 464 48 WIRE 624 48 624 0 WIRE 624 48 560 48 WIRE 720 64 720 16 WIRE 1216 64 1216 32 WIRE -480 80 -480 16 WIRE 624 96 624 48 WIRE 1088 112 1088 16 WIRE 1360 112 1360 80 WIRE 1360 112 1088 112 WIRE 1504 112 1504 64 WIRE 1504 112 1360 112 WIRE 1648 112 1648 64 WIRE 1648 112 1504 112 WIRE 1360 128 1360 112 WIRE -480 144 -480 80 WIRE 528 144 528 128 WIRE 160 160 160 112 WIRE 464 160 464 48 WIRE 496 160 464 160 WIRE -400 176 -416 176 WIRE -304 176 -400 176 WIRE -144 176 -224 176 WIRE 96 176 96 -160 WIRE 96 176 -64 176 WIRE 128 176 96 176 WIRE 624 176 624 96 WIRE 624 176 560 176 WIRE -416 192 -416 176 WIRE 240 192 192 192 WIRE 288 192 240 192 WIRE 496 192 368 192 WIRE 128 208 64 208 WIRE 1360 240 1360 208 WIRE 528 256 528 208 WIRE 160 272 160 224 WIRE 368 288 368 192 WIRE 368 432 368 368 FLAG 368 496 0 FLAG 352 0 0 FLAG -544 -112 0 FLAG -480 -304 p15 FLAG 160 112 p15 FLAG 352 -272 p15 FLAG 720 -80 p15 FLAG 528 128 p15 FLAG -480 80 n15 FLAG 160 272 n15 FLAG 528 256 n15 FLAG 720 64 n15 FLAG 1008 -16 IntOut FLAG -416 272 0 FLAG 64 208 0 FLAG -400 176 in FLAG 240 192 u1out FLAG 624 96 u2out FLAG 592 -80 j1out FLAG 208 -400 cout FLAG 1888 -304 0 FLAG 1216 64 p15 FLAG 1216 -80 n15 FLAG 1360 240 0 FLAG 1728 0 out SYMBOL Opamps\\LT1001 160 128 R0 SYMATTR InstName U1 SYMBOL Opamps\\LT1225 528 112 R0 SYMATTR InstName U2 SYMBOL Opamps\\LT1225 720 -80 R0 SYMATTR InstName U3 SYMBOL res 384 176 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R1 SYMATTR Value 33k SYMBOL res 352 272 R0 SYMATTR InstName R2 SYMATTR Value 100 SYMBOL cap 352 432 R0 SYMATTR InstName C1 SYMATTR Value 2.2µ SYMBOL res -208 160 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R3 SYMATTR Value 50k SYMBOL cap 560 32 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C2 SYMATTR Value 100p SYMBOL res 480 -96 R0 SYMATTR InstName R4 SYMATTR Value 1.5k SYMBOL res 336 -96 R0 SYMATTR InstName R5 SYMATTR Value 475 SYMBOL njf 304 -224 R0 SYMATTR InstName J1 SYMATTR Value U309 SYMBOL res 832 -160 R0 SYMATTR InstName R6 SYMATTR Value 243 SYMBOL cap 928 -128 R0 SYMATTR InstName C3 SYMATTR Value 100p SYMBOL cap 880 -256 R0 SYMATTR InstName C4 SYMATTR Value 330p SYMBOL voltage -480 -256 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V1 SYMATTR Value 15 SYMBOL voltage -480 -80 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V2 SYMATTR Value 15 SYMBOL voltage -416 176 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V3 SYMATTR Value 0 SYMBOL sw 1792 -288 R180 SYMATTR InstName S1 SYMATTR Value MYSW SYMBOL voltage 1936 -400 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V4 SYMATTR Value PULSE(1 0 0.5u) SYMBOL Opamps\\LT1225 1216 64 M180 SYMATTR InstName U4 SYMBOL res 1344 -16 R0 SYMATTR