Searching the "best" CCS - Page 2

mikeks · 16th September 2006, 07:37 PM

http://www.diyaudio.com/forums/showt...288#post726288

http://www.diyaudio.com/forums/showt...997#post726997

http://www.diyaudio.com/forums/showt...712#post727712

http://www.diyaudio.com/forums/showt...514#post728514

MikeB · 16th September 2006, 07:39 PM

Thanks jcx, out of words ?

Boot_fet seems to be difficult to feed a diffamp as i can't easily bootstrap to the swinging emitters node, but cascoded jfet ccs seems to be really the king...

Mikeks, thanks, i really need to improve my searching skills...

Mike

MRupp · 16th September 2006, 08:00 PM

Mike, here is an intresting CCS variation, might be worth investigating further: http://www.elektronik-kompendium.de/...r/curr2pol.htm

MikeB · 16th September 2006, 08:23 PM

Hi Martin, thanks for the link. I have a nearly identical version in my collection, except your r3/4. R3 is really interesting, there is a good chance that the ccs would keep closed at startup. I experimented with r4, but all kind of values only reduced quality ?

Mike

MikeB · 16th September 2006, 09:14 PM

I made more sims, also adding the "self cascoding" jfet ccs. (see attachment)
The self cascoding shows an impressive -114db...

Than i ran a transient analysis to check stability of these circuits.
I quickly rejected the "self cascoding", it has ringing like hell, asking for problems. Also i rejected all circuits showing any ringing or beeing ugly slow, this left over 3 circuits, the zener referenced ones and the cascoded jfet.
Number 7 (the cascoded jfet) seems to be best option regarding psrr AND stability. (the most stable one)
2nd choice would be Number 3, simple but efficient and stable. Better than my favourite (until today), the No1....

Mike

mfc · 16th September 2006, 09:18 PM

Try Supertex DN2540 (3ma), or LND150 (1ma).
In JCX circuit it reduces another -25db or more.

MikeB · 16th September 2006, 09:20 PM

I am not familair with these devices, are these current regulator diodes ?

Mike

mfc · 16th September 2006, 09:49 PM

DN2540 data sheet

They are hi-voltage.

Spice model is available on their website as well.

MikeB · 16th September 2006, 09:55 PM

Ah, depletion mode mosfets.. Thanks !

Mike

jcx · 16th September 2006, 09:59 PM

R5/R4 = R2/R1 (trimmed R4 for estimated D1 Zener dynamic Z of ~ 15 Ohm)

1KHz on V4 positive supply probes probes psrr

3KHz at V3 input tests input cmrr

plot Id(J2)*1000
for same display/"units" as earlier posts, ~ 115 dB psrr, 140dB input cmrr

16th September 2006, 08:00 PM	#13
MRupp diyAudio Member Join Date: Dec 2003 Location: Frankfurt area	two pole CCS Mike, here is an intresting CCS variation, might be worth investigating further: http://www.elektronik-kompendium.de/...r/curr2pol.htm __________________ Martin Rupp

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16th September 2006, 07:37 PM	#11
mikeks Account Disabled Join Date: Jun 2004 Location: Animal farm	http://www.diyaudio.com/forums/showt...288#post726288 http://www.diyaudio.com/forums/showt...997#post726997 http://www.diyaudio.com/forums/showt...712#post727712 http://www.diyaudio.com/forums/showt...514#post728514

16th September 2006, 07:39 PM	#12
MikeB diyAudio Member Join Date: Apr 2004 Location: Gütersloh	Thanks jcx, out of words ? Boot_fet seems to be difficult to feed a diffamp as i can't easily bootstrap to the swinging emitters node, but cascoded jfet ccs seems to be really the king... Mikeks, thanks, i really need to improve my searching skills... Mike

16th September 2006, 08:23 PM	#14
MikeB diyAudio Member Join Date: Apr 2004 Location: Gütersloh	Hi Martin, thanks for the link. I have a nearly identical version in my collection, except your r3/4. R3 is really interesting, there is a good chance that the ccs would keep closed at startup. I experimented with r4, but all kind of values only reduced quality ? Mike

16th September 2006, 09:18 PM	#16
mfc diyAudio Member Join Date: Jun 2004 Location: Oregon	Try Supertex DN2540 (3ma), or LND150 (1ma). In JCX circuit it reduces another -25db or more.

16th September 2006, 09:20 PM	#17
MikeB diyAudio Member Join Date: Apr 2004 Location: Gütersloh	I am not familair with these devices, are these current regulator diodes ? Mike

16th September 2006, 09:49 PM	#18
mfc diyAudio Member Join Date: Jun 2004 Location: Oregon	DN2540 data sheet They are hi-voltage. Spice model is available on their website as well.

16th September 2006, 09:55 PM	#19
MikeB diyAudio Member Join Date: Apr 2004 Location: Gütersloh	Ah, depletion mode mosfets.. Thanks ! Mike

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