Magnetic bubble memory linear interface circuits

Two bipolar integrated circuits are described which provide the write and sense functions required by magnetic bubble memory systems, both organized in four-channel format to minimize board area occupied. The write driver circuit has a 300 mA drive capability and includes on-chip circuitry which prevents fusing of the delicate bubble `hairpin' structure under fault conditions. The sense amplifier has programmable sensitivity in the range of 1 mV to 10 mV and allows the bubble device to be directly coupled to the differential input while tolerating DC offsets of up to /spl plusmn/150 mV without significantly modifying sensitivity.