The generation of rotating magnetic fields for bubble devices

This paper is concerned with the generation of the rotating in-plane magnetic field which is required by field-accessed bubble devices. We discuss both the design of the field coils as well as the drive circuitry which is required to produce transient-free starting and stopping of the rotating field. Details of coil design are given for a multichip 1 Mbit module and a small (0.25 sq. cm) single chip memory. The circuitry required to drive these coils at 1OO kHz and 1 MHz is discussed in detail.