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Old 11th May 2013, 10:44 AM   #21
matze is offline matze  Germany
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Quote:
Originally Posted by dadod View Post
Hi Matthias,
Here is the gain plot without output buffer. First one is without C2 and second with C2.
BR damir
Hi Damir,

thanks. Cascoding often seems to require some extra tricks. Here in the current mirror, there in the buffer.

Kind regards,
Matthias
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Old 11th May 2013, 10:49 AM   #22
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Hi Matthias,
Here is the gain plot without output buffer. First one is without C2 and second with C2.
BR damir
I have to wonder whether that peaking is not coming from the current mirrors. All current mirrors have some peaking around the 2-15 Mhz. The EF assisted mirror has much higher peaking than the standard one.

You could try placing small value cap from base to emitter of Q21 and Q22.
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Old 11th May 2013, 12:04 PM   #23
dadod is offline dadod  Croatia
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Originally Posted by manso View Post
Interesting, some performance is lost. Can it be made stable if you remove the zobel and only the RC in place ??
I think it's possible, but I am more interested in simpler output buffer and I will show you what I've found later.
Damir
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Old 11th May 2013, 12:11 PM   #24
dadod is offline dadod  Croatia
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Originally Posted by manso View Post
I have to wonder whether that peaking is not coming from the current mirrors. All current mirrors have some peaking around the 2-15 Mhz. The EF assisted mirror has much higher peaking than the standard one.

You could try placing small value cap from base to emitter of Q21 and Q22.
It helps, the peaking no more, but I don't like the brick wall like plot, and if I keep C2 connected it looks much smoother.
Damir
Attached Images
File Type: jpg GainWire-mk2-e-elvee-dado-gainpeaking-noC2.jpg (242.4 KB, 591 views)
File Type: jpg GainWire-mk2-e-elvee-dado-gainpeaking-C2.jpg (236.7 KB, 563 views)
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Old 11th May 2013, 12:18 PM   #25
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It helps, the peaking no more, but I don't like the brick wall like plot, and if I keep C2 connected it looks much smoother.
Damir
Any of those measures will suffice indeed.
I asked mainly because some have no knowledge about the peaking in current mirrors and this is a very good example of where these anomalies many times originate.

Simpler than diamond buffer ?? I think thats as simple as can be had for such performance.
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Old 11th May 2013, 12:49 PM   #26
dadod is offline dadod  Croatia
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Originally Posted by manso View Post
Any of those measures will suffice indeed.
I asked mainly because some have no knowledge about the peaking in current mirrors and this is a very good example of where these anomalies many times originate.

Simpler than diamond buffer ?? I think thats as simple as can be had for such performance.
Could you take a look at first post in this thread and tell me what you think about that output buffer?
Damir
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Old 11th May 2013, 02:36 PM   #27
dadod is offline dadod  Croatia
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This is schematic I like the most, with simple output buffer.

THD1k at 2 V output is just 0.000066%
Output impedance is 23 ohm flat from DC up to 100 kHz
I kept output resistor, now lower at 22 ohm, to be less sensitive to the long cable capacitance
PSRR abouth 90 dB
Damir
Attached Images
File Type: jpg GainWire-mk2-e-3-FFT.jpg (204.0 KB, 554 views)
File Type: jpg GainWire-mk2-e-3-outputimpedance.jpg (238.8 KB, 514 views)
File Type: jpg GainWire-mk2-e-3-PSRR.jpg (234.3 KB, 474 views)
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Old 12th May 2013, 09:40 PM   #28
dadod is offline dadod  Croatia
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No comments on this simple output buffer?
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Old 13th May 2013, 07:28 AM   #29
dadod is offline dadod  Croatia
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100 kHz square wave simulation.
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Old 14th May 2013, 12:31 PM   #30
dadod is offline dadod  Croatia
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This shunt regulator(stabilizer) could be used as the power supply for this lineamp.
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