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Constant Current Source (CCS) For Audio Applications
Constant Current Source (CCS) For Audio Applications
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Old 28th July 2016, 11:26 AM   #11
AndrewT is offline AndrewT  Scotland
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I copied and moved the two models.text files to my LTspicefiles folder.
I opened the .asc
"run" but it can't find the models.
Where do I put the .txt files so that the .asc can find them?
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Last edited by AndrewT; 28th July 2016 at 11:46 AM.
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Old 28th July 2016, 11:36 AM   #12
padamiecki is online now padamiecki  Poland
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this might be helpfull: ????(sijosae) - [??] Constant Current Source (CCS) ?? ??? - 2?
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Old 28th July 2016, 01:00 PM   #13
mt490 is offline mt490
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Try a 5k1 + 220uF bootstrap for size.
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Old 28th July 2016, 01:20 PM   #14
Mosquito is offline Mosquito  Argentina
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Quote:
Originally Posted by AndrewT View Post
Where do I put the .txt files so that the .asc can find them?
same folder where .asc is, You can check opening the .txt from the open simulation window (double click on the .include xxx.txt (lib/inc editor.. open)

Last edited by Mosquito; 28th July 2016 at 01:23 PM.
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Old 28th July 2016, 01:46 PM   #15
erikovsky is offline erikovsky
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Quote:
Originally Posted by erikovsky View Post
Just found a paper:
Low noise constant current source for bias dependent noise measurements
D. Talukdar et al.

A low noise constant current source used for measuring the 1/f noise in disordered systems in ohmic as well as non-ohmic regime is described. The source can supply low noise constant current starting from as low as 1 μA to a few tens of mA with a high voltage compliance limit of around 20 Volts. The constant current source has several stages which can work in a standalone manner or together to supply the desired value of load current. The noise contributed by the current source is very low in the entire current range. The fabrication of a low noise voltage preamplifier modified for bias dependent noise measurements and based on the existing design available in the MAT04 data sheet is also described.

Here's my results with the schematic on the paper.
Y-axis: decibel
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File Type: gif CCS3.gif (11.2 KB, 643 views)

Last edited by erikovsky; 28th July 2016 at 01:58 PM.
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Old 28th July 2016, 02:19 PM   #16
jkuetemann is offline jkuetemann  Canada
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Quote:
Originally Posted by xrk971 View Post
Nice thread!

We can add the shunt voltage reference CCS. So either a Zener diode or a programmable reference like the TL431. I hear that the TL431 is supposedly quieter than a Zener as it doesn't have the Zener switch noise. The shunted voltage the controls then base of the CCS transistor.
Yes the TL431 is definitely an option. I haven't yet procured a model for the device that works in LTspice yet. Admittedly I haven't looked too hard either.
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Old 28th July 2016, 02:22 PM   #17
jkuetemann is offline jkuetemann  Canada
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Quote:
Originally Posted by jerluwoo View Post
The op's sim is flawed since R4/5 are fed ac as well. They should be connected to a dc source with no ac signal.
Noted. I will set up a sim with a stable bias source and see how they look.

Edit: Changes the results quite a bit. Things actually look closer to how I would expect. Thanks for pointing out my error.
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File Type: png CCS Compared Alt Bias.png (120.8 KB, 642 views)
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Last edited by jkuetemann; 28th July 2016 at 02:34 PM. Reason: Added sim screen shot.
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Old 28th July 2016, 02:25 PM   #18
Mark Johnson is offline Mark Johnson  United States
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Constant Current Source (CCS) For Audio Applications
An under-appreciated attribute of current source (Q2/Q3/nodeB) from post #1 is: extremely high output impedance thanks to negative feedback. Much higher than the 1T circuit Bob Cordell recommends (6.3V zener drops 5.6V across emitter resistor) to people who seek high output impedance. Careful / clever choice of R5, or R5 replacement, gives excellent PSRR too.
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Old 28th July 2016, 02:40 PM   #19
jkuetemann is offline jkuetemann  Canada
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Quote:
Originally Posted by Mark Johnson View Post
An under-appreciated attribute of current source (Q2/Q3/nodeB) from post #1 is: extremely high output impedance thanks to negative feedback. Much higher than the 1T circuit Bob Cordell recommends (6.3V zener drops 5.6V across emitter resistor) to people who seek high output impedance. Careful / clever choice of R5, or R5 replacement, gives excellent PSRR too.
Can you offer any insight into optimizing the 2 BJT biasing arrangement?
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Old 28th July 2016, 03:26 PM   #20
jerluwoo is offline jerluwoo  United States
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Although you won't see any improvement in sims with perfect dc rails, in a real world circuit with noise this can have a major improvement in psrr.
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