The sense amplifier common mode effect on a switching current-mode power staged based on sigma-delta modulation

In this paper the behaviour of a sigma-delta current loop in a switching power stage is examined by focusing on its current sensing characteristics. In particular the influence of the current sensing common mode gain on system behaviour has been analyzed. The system was tested by applying it to a hard disk voice coil motor. The system works well in this application as the current sensing specifications it has to comply with are less stringent than alternative solutions.