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Old 24th June 2013, 08:44 PM   #61
dadod is offline dadod  Croatia
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Originally Posted by RCruz View Post
Q4 is a "helper" right ?
Right.
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Old 2nd July 2013, 05:15 AM   #62
dadod is offline dadod  Croatia
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Here is the schematic with DC servo and now it is DC preamp with stable zero offset at the output.
RCruz how is going with preparation?
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Old 2nd July 2013, 05:55 AM   #63
RCruz is offline RCruz  Switzerland
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Other projects on going.... will keep you posted
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Old 3rd July 2013, 03:22 PM   #64
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Dadod,

Here is a page I copied from the texas european patent some years back that I kept for reference. There is a small difference though and I wonder how much difference it makes to performance. In the patent I remember they claimed a 10x improvement in impedance over a cascoded current mirror.
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Old 3rd July 2013, 09:17 PM   #65
dadod is offline dadod  Croatia
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Dadod,

Here is a page I copied from the texas european patent some years back that I kept for reference. There is a small difference though and I wonder how much difference it makes to performance. In the patent I remember they claimed a 10x improvement in impedance over a cascoded current mirror.
Thanks Manso, it is not the same, for me it looks quite different, I should try this one too.
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Old 4th July 2013, 05:06 AM   #66
dadod is offline dadod  Croatia
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This version I called mk3, it's simpler and with a bit higher distortion then mk2, and uses JFETs in the input, possible not so easy obtainable. It's run on +-20V and DCservo opamp could use the same power supply with no need to lower the voltage.
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Old 4th July 2013, 03:08 PM   #67
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Thanks Manso, it is not the same, for me it looks quite different, I should try this one too.
The only difference is that they connect the baxandall cascode`s input to the mirrors base and not the mirrors input.

Interesting, looking forward to your findings.
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Old 4th July 2013, 03:19 PM   #68
dadod is offline dadod  Croatia
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Originally Posted by manso View Post
The only difference is that they connect the baxandall cascode`s input to the mirrors base and not the mirrors input.

Interesting, looking forward to your findings.
I simulated it and I've got almost the same distortion as with the mirror I am using. Does that difference is enough to prevent patent infringement?
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Old 4th July 2013, 03:38 PM   #69
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I simulated it and I've got almost the same distortion as with the mirror I am using. Does that difference is enough to prevent patent infringement?


There must be someting to it. I wonder about mirror peaking, they dont suggest compensation of this mirror. The best would be to sim it in isolation to be sure.

For Diy there isnt any problem in using it though. Texas instruments btw must be very suspicious fellas, many of their patents have both european and US registries for the same patent.
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Old 4th July 2013, 04:35 PM   #70
dadod is offline dadod  Croatia
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Originally Posted by manso View Post


There must be someting to it. I wonder about mirror peaking, they dont suggest compensation of this mirror. The best would be to sim it in isolation to be sure.

For Diy there isnt any problem in using it though. Texas instruments btw must be very suspicious fellas, many of their patents have both european and US registries for the same patent.
I simulatid the gain stage with TI mirror and my mirror and there is peaking in both of them without any compensation. TI looks a bit better??
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