I am currently using the DRV8825 (https://www.oyostepper.es/goods-887-5-PiezasPaquete-DRV8825-M%C3%B3dulo-de-controlador-paso-a-paso-con-disipador-de-calor-para-impresora-3d-Reprap.html) in some prototype electronics that include sensitive analog imaging electronics. Imaging systems have noise levels in the 10s of μV range and my stepper motor drivers are injecting noise through a common PSU. Now, I did design the circuit correctly, using a good LDO to power the imaging sensor, using ferrite beads and plenty of decoupling, but there is some noise coupling there.

I do have some ideas on how to improve this from a PSU architecture perspective, but I wanted to explore the idea of ​​a linear stepper motor driver driven by a high frequency PWM generated by an FPGA that is filtered to a sine wave. This would drive a class AB amplifier stage or buffer for the stepper motor. The motor is a small NEMA 11, running at reasonable RPM and very light load, so it only consumes 1-2W.

Ideally, I'd like this circuit to be around $2 in 1k quantity. I think the best route might just be some discrete transistors in a class B setup. Does anyone have experience with this? Is this something a fool would do?

Thanks!