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Jfet folded cascode with diamond buffer opamp
Jfet folded cascode with diamond buffer opamp
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Old 27th May 2011, 08:29 AM   #11
sonnya is offline sonnya  Denmark
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Default jfet opamp module simulation data

Hi all.

I have attached the simulation data.
Attached Images
File Type: jpg 2xgain.jpg (245.8 KB, 636 views)
File Type: jpg 11xgain.jpg (238.3 KB, 602 views)
File Type: jpg 101xgain.jpg (247.3 KB, 554 views)
File Type: jpg CLGx1+100pFComp.jpg (237.2 KB, 403 views)
File Type: jpg CLGx1+100pFComp+220pF.jpg (247.5 KB, 364 views)
File Type: jpg CLGx11+1nF.jpg (251.0 KB, 47 views)
File Type: jpg CLGx11+47pFComp+220pF.jpg (253.4 KB, 54 views)
File Type: jpg OLG+220pF.jpg (253.1 KB, 54 views)
File Type: jpg OLG+470pF.jpg (257.3 KB, 53 views)
File Type: jpg OLG+1nF.jpg (257.6 KB, 70 views)
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Old 27th May 2011, 08:34 AM   #12
sonnya is offline sonnya  Denmark
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The sim data should speech for them self.

The supply voltage is +/-15V

When compensation is added it is added from "COMP" to V-.

Source:50Ohm.

Feedback for x11:10K+1K
Feedback for x101:10K+100R
Feedback for x1:1K

The picture "CLGx11-47pfcomp-22pF-1vppstep" is a 220pF load and not 22pF
Attached Images
File Type: jpg openloopgain.jpg (254.7 KB, 95 views)
File Type: jpg CLGx11+1vppstep.jpg (194.8 KB, 63 views)
File Type: jpg CLGx11+220pF+1vppstep.jpg (198.3 KB, 43 views)
File Type: jpg CLGx11+47pFComp+22pF+1Vppstep - sim B.jpg (183.3 KB, 43 views)
File Type: jpg CLGx11+47pFComp+220pF+1Vppstep - sim A.jpg (198.9 KB, 43 views)

Last edited by sonnya; 27th May 2011 at 08:38 AM. Reason: wrong picture name
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Old 27th May 2011, 09:08 AM   #13
sonnya is offline sonnya  Denmark
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Default FFT 1KHz out

1Kohm Load at 1KHz and 1Vpp and 11Vpp.
Attached Images
File Type: jpg 1vpp+1kload+1KHz - sim B.jpg (171.6 KB, 125 views)
File Type: jpg 11vpp+1kload+1khz.jpg (186.4 KB, 126 views)
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Old 27th May 2011, 10:15 AM   #14
MiiB is offline MiiB  Denmark
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How does it sim at 20 KHz..??
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Old 27th May 2011, 11:25 AM   #15
sonnya is offline sonnya  Denmark
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Hi MiiB.

Here the 20KHz at 1Vpp and 11Vpp is shown also with 1K load.

I am satisfied with result myself.

- Sonny
Attached Images
File Type: jpg 11vpp+1kload+20khz.jpg (157.2 KB, 140 views)
File Type: jpg 1vpp+1kload+20KHz.jpg (157.6 KB, 128 views)
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Old 28th May 2011, 06:17 AM   #16
sonnya is offline sonnya  Denmark
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Default Noiselevel of jfet opamp

The last one. with noise levels at 1x 11g gain.

- Sonny
Attached Images
File Type: jpg noise at CLGx1.jpg (192.8 KB, 105 views)
File Type: jpg noise at CLGx11.jpg (195.4 KB, 77 views)
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Old 29th May 2011, 06:02 AM   #17
sonnya is offline sonnya  Denmark
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Quote:
Originally Posted by MiiB View Post
How does it sim at 20 KHz..??
Did you get what you asked me about?
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Old 29th May 2011, 06:55 AM   #18
Nelson Pass is offline Nelson Pass  United States
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Jfet folded cascode with diamond buffer opamp
Have you considered a little more voltage drop than provided by D2?

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Old 29th May 2011, 07:44 AM   #19
sonnya is offline sonnya  Denmark
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There are two versions of it.

The first one, which you refer too with folded cascode and the one with wilson mirror in post 7 (Easier to implement on the small pcb).

I have tried with a LED as D2 as weel for simulation. And there is no difference. But we also have .65V CE drop across U5-A and U5-B. This also works good for current mirrors and hawksford cascode which i use in my CFB amp.
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Old 21st June 2011, 11:33 PM   #20
sonnya is offline sonnya  Denmark
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Now i have had time to order pcb and stencils.

They will arrive in week 27.

I will make a motherboard for them to test them.
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