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Elvee 11th March 2011 12:36 PM

Halve the diamond, double the performance!!!
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Here is what is basically a Taylor half-diamond follower, but with a twist: Q4 and Q5 take care of the positive part of the signal, ensuring symetrical performance, and smooth class B operation:

jam 11th March 2011 04:06 PM

Holding the input constant what is the worst case oamffset (drift)?
It does look like a novel idea.


Elvee 11th March 2011 04:41 PM


Originally Posted by jam (
Holding the input constant what is the worst case oamffset (drift)?

In this example, it is approximately 50mV (Q1 and Q3 held at the same temperature).

It depends on the matching of the current densities in Q1 and Q3. If the currents are scaled in the same proportion as the junction areas, a first order cancellation occurs, both statically and dynamically.

AKSA 18th September 2011 01:59 PM

Brilliant, Elvee!

Have you built and auditioned it?


Elvee 18th September 2011 05:20 PM


Originally Posted by AKSA (
Have you built and auditioned it?

Yes, I have built it, tested it with real audio too: no obvious flaw.
I won't comment further in that direction since I have tin ears, but it sounds OK.

It is not a topology for the faint hearted though: the input impedance is negative, which can be disconcerting to the novice.

kenpeter 18th September 2011 11:21 PM

You know the base current of 2n3055 is wildly not a linear load.
Somehow need to add or subtract that drive current back into
the equation that will hold Q1's emitter drop constant.

Bigun 19th September 2011 12:01 AM

I like it !

reminds me a little bit of this: Amplifier Variations.

kenpeter 19th September 2011 12:02 AM

1 Attachment(s)
Easier way to hold half diamond emitters at constant voltage drop...
Taylor still worth knowing, please keep exploring the original circuit.

kenpeter 19th September 2011 12:52 AM

1 Attachment(s)
Or this way too, could hold those two emitters constant.
You might ask, why not a simple mirror across the top?
Yeah, but a mirror isn't so easy to bootstrap. Or is it???
M2 might want gate swing a few volts above the rail.

I keep trying to throw a gratuitous Taylor in there,
other weird solutions just keep popping in my head.
At least we are watching a collector and bouncing
that info as current to an active load on the emitter...

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