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Old 8th February 2009, 08:37 PM   #1
martyh is offline martyh  United States
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Default Will this work as a differential stage?

Probably a silly question but would this work to get a low impedance differential drive?
Thanks,
Marty

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Old 8th February 2009, 08:48 PM   #2
EC8010 is offline EC8010  United Kingdom
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Not terribly well, I think. The cathode followers are fine but the CCS isn't. Think about what would happen if the signal currents in the two valves were not equal - a very large signal voltage would develop across the CCS. What you'd really like is a current mirror in the cathodes.
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Old 8th February 2009, 11:01 PM   #3
martyh is offline martyh  United States
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Thanks, I guess it was a silly question. A search on the forum for “current mirror” turned up plenty of threads where the idea I just drew was discussed at length.
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Old 9th February 2009, 07:13 AM   #4
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You're welcome.
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Old 9th February 2009, 07:54 AM   #5
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Hi Martyh

The circuit you are proposing is a differential cathode follower !? I had not heard of it until recently, when it was extensively discussed in this thread

Erik
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