Amp design recommendation
I am no expert at motor control, but I think you are on the wrong track in a few ways:

An op-amp is probably not the best way to do this, but if you want to do it that way, using a 120 MHz op-amp for a circuit that probably needs a few 10's of Hz of bandwidth is probably not the right choice. You could probably do this with a $0.05 LM2904B (with a transistor buffer on the output).

Current feedback op-amps were designed to obtain higher frequency performance from older manufacturing processes. They have some design quirks and require special design consideration. But since you don't need 100 MHz or higher bandwidth, you can avoid the whole problem by using an ordinary voltage-feedback op-amp.

Since your output voltage is always above 0 V, you don't need a negative supply.


But in any case, the op-amp design will be fairly inefficient, burning power as heat to reduce the supply voltage to whatever voltage you are delivering to the motor. A more efficient solution, if you don't need exceptional accuracy in the voltage divide ratio from the input to the motor, would just use a PWM circuit, with 50% duty cycle. If the motor can't handle a PWM drive directly (this is where you need someone who knows motors better than me), then you can filter the signal with an LC filter.



simulate this circuit &ndash; Schematic created using CircuitLab