Descreet OTA from CA3096

[Jim Patchell]

    I used the CA3096 as an OTA quite a long time ago.  It's rejection of
control current is probably about on par with using a CA3080.  I felt that in
the long run, it was easier to use the 3080, since at the time, it was
difficult to easily get the CA3096, and the CA3096AE, which has better
matching, was a bit pricey.  As I recall, it was about $2.00, but that was back
in 1976.  I noticed that the part is availible from several mail order places,
but none seems to offer the 'A' version.

    The applications I used it in were for state variable filters and VCA's.  I
used the extra NPN transistor that was left over to keep the positive voltage
one diode drop above ground for the current mirror.  This seemed to help a lot
in keeping leakage down to a minimum, but limited it's use to going into a
virtual ground of an opamp input.

    -Jim

jhaible wrote:

> > It's a basic building block, and with two CA3096 arrays you can build all
> > these things and many others.
>
> Another thing I wanted to try but didn't find the time yet. Can you tell us
> about the performance of the 3096-based version ? Offset variation
> over Iabc in particular? I mean, are the pnp's good enough to form
> a precise current mirror that keeps its symmetry over several decades ?
>
> JH.