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Offset Compensated Emitter-follower...
Offset Compensated Emitter-follower...
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Old 4th June 2006, 08:16 PM   #1
mikeks is offline mikeks  United Kingdom
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Smile Offset Compensated Emitter-follower...

See attached...
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Old 4th June 2006, 08:50 PM   #2
darkfenriz is offline darkfenriz  Poland
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Looks like variation on Sziklai connection. How does it perform?
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Old 4th June 2006, 08:56 PM   #3
mikeks is offline mikeks  United Kingdom
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Quote:
Originally posted by darkfenriz
Looks like variation on Sziklai connection.
Nope...


Quote:
Originally posted by darkfenriz

How does it perform?
Q1 is the emitter follower...Q2 is the diode which provides offset compensation....The current mirror provides bias for the diode....probably good idea to bypss it with 1uF to the +supply rail.
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Old 4th June 2006, 09:19 PM   #4
Ultima Thule is offline Ultima Thule  Europe
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Mike,

where do you find it's application?
It seem to have only current amplification, is it much better than an emitter follower for instance except that a single emitter follower introduce an offset?

Cheers Michael
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Old 4th June 2006, 09:26 PM   #5
mikeks is offline mikeks  United Kingdom
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Quote:
Originally posted by Ultima Thule
.....an emitter follower........except that a single emitter follower introduce an offset?

Cheers Michael

Yup...
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Old 4th June 2006, 09:32 PM   #6
sawreyrw is offline sawreyrw  United States
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Mike,

I'm pretty sure this circuit will burn up in a few msec, if you actually build one. The current through Q7 will be over .3 amps, so it's power dissapation will be over .3*22=6.6 watts.

Rick
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Old 4th June 2006, 09:32 PM   #7
poobah is offline poobah  United States
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Any significant output current will imbalance the emitter currents and therefore the Vbe.

It generally not the offset in emitter followers that upsets things... rather it is the fact the offset is nonlinear function of current.

Am I missing something here?



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Old 4th June 2006, 09:33 PM   #8
mikeks is offline mikeks  United Kingdom
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Quote:
Originally posted by sawreyrw
Mike,

I'm pretty sure this circuit will burn up in a few msec, if you actually build one. The current through Q7 will be over .3 amps, so it's power dissapation will be over .3*22=6.6 watts.

Rick
Where did you get 0.3Amps???


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Old 4th June 2006, 09:34 PM   #9
mikeks is offline mikeks  United Kingdom
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Quote:
Originally posted by poobah
Any significant output current will imbalance the emitter currents and therefore the Vbe.

It generally not the offset in emitter followers that upsets things... rather it is the fact the offset is nonlinear function of current.

Am I missing something here?



Try it...


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Old 4th June 2006, 09:46 PM   #10
Ultima Thule is offline Ultima Thule  Europe
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..and this one not good enough?

EDIT: Had to redraw, was too quick..
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