thus using my simple cct and sig gen, you can get results immediately now with any 8 bit DSO and then use XY mode with phase and get speed limit or C vs V bias and on/off R ratio for different pre-programmed parameters and then decide what if any enhancements you need with custom PCB.
If you. need higher current limits than an OA can give , using complementary emitter followers inside the loop output with smaller R values is possible or anything, if , you specify the interface, V,I,t constraints.
After all, you can scale 8 bits over any range you need, which ought to be sufficient for testing a binary memristor