>>3935645It's not quite the same.
The Pentax PLM and DC motors are more akin to Tamron RXD and OSD.
These are different variations of stepper motors, configured with different levels of torque power.
Some of them are silent, but have other drawbacks.
The Sony XD Linear are more akin to Tamron's VXD lenses, they don't use motors, but they use electromagnetic actuators.