[sdiy] Replacing CA3080 with CA3046 ??

[srnovak at ncsu.edu]

Hi group.
I'm somewhat new to the list so sorry if this suggestion has been made
before....

Has anyone tried to build an OTA out of a CA3046? I was looking at the
schematic on the 3080 datasheet and if seems like if one were to replace
the bias transistors with the appropriate resistors it would be possible.
So here's my idea:

Q1 & Q2 make a the differential input stage
Q3 collector connects to Q1 & Q2 emitters and provides bias current to
adjust gain.
Q4 common source amplification stage
Q5 commons drain voltage follower.

This of course omits external resistors for bias current, but these could
be tailored to each individual circuit and furhter control over the gain
of each stage.

If this works one advantage would be the ability to omit another opamp
stage to change the current from the OTA to a voltage. I guess this is
idea isn't so much an OTA as a OPAMP with gain programmable by a current.

Any thoughts??