OTA / Common Base (CB) Transistor Circuit
I will try to answer more generally. I am not sure wether your circuit even works, but I will try to lay it out in more broad therms because I actually saw some of those things in other working circuits:

The control input of an OTA is typically current driven – in case of a OTA like the LM13700 these currents should generally be very small.

The current used to control the gain of the OTA does so in linear fashion, that is why there is a PNP-transistor used in this circuit: it is an exponential converter. Note that it is advised to use two transistors (aka a Exponential pair) if it is critical to avoid temperature drift (this was tyically used to avoid drift in analog VCOs).

I am not sure for what reasons you are using this circuit, but if you are searching for a VCA circuit with exponential control, you might also have a look at the V2164 or the THAT2181 which are a bitharder to get, but they do the exponential conversion for you, have a higher dynamic range than a OTA and way less harmonic distorsion.