I need to "duplicate" a given current: it has to feed two IC's. The context is an OTA (operational transconductance amp) whose gain is controlled by a bias current. Concretely, I am considering the CA3280 (or the modern LM13700). Since I have at my disposal two amplifiers in the same IC, I would like to connect them in parallel in order to halve the noise.
The problem is how to send the same (given) bias current to both amps: if the bias is "incoming" I cannot use a current mirror, since it would behave as a "sink", thus producing a current coming out from the amps. I need a current source instead - kind of "inverting" the current mirror.
Hope the problem is understandable. Any idea?