[sdiy] discrete SSM2018?

[jh.]

>1:0 for Haible. There is really no reason why this should work.
>Except for temperature dependence, but also this is not valid.

1:0 ? Hardly. Actually, I have no idea what's going on in a
chip design when a tight matching is attempted.
So, another question, quite contrary to the first one:
The overall gm of an OTA also depends on the current transfer
ratio of the current mirrors. This is also related to an "offset"
voltage between two transistors of the mirror. Now how do
they manage to match *this* from amplifier to amplifier?
Or how do they manage to match the npn and pnp mirrors
in one OTA, to start with ? I mean, how can they do *this*,
while they cannot spec the gm of one OTA tightly ?
(Assuming the gm of the input pair is not the problem,
as it follows a fundamental rule, depending on Iabc.)
This looks like matching across the chip would be easier than
matching two parts of one mirror, which is hardto believe.
Any ideas ?

JH.