Minoru Hiroshima

Some aspects of permalloy chevron strip detector

The response of thick‐permalloy chevron‐strip detector (287 columns) on YSm garnet (6.5μ stripe width) has been examined for the cases of dc and pulse current drives in high detector current region.Relations between a detector window Vw (defined as a voltage difference between the ONE and Zero states) and a detector current Id are shown in Fig. 1. These data were obtained from a 100kHz module operation of 16k‐bit major‐minor organized chips by changing the ratio between a pulse width tw and a pulse period tp.In all cases, saturation of Vw was observed. The maximum Vw for tw/tp=0.5/20 μs became 5 times higher than that for dc. Also, it was observed that a replicator acted as a nucleation type generator when the dc current of 8mA was applied. Present experiments have shown that these observed phenomena can be explained by considering the temperature rise of the of the garnet film heated by the detector.

Design and Evaluation of 64 kbit Magnetic Bubble Memory Chip

A 64 kbit bubble memory chip is designed, fabricated, and tested. The chip contains 128 minor loops, each with 513 bits. The circuit period is 20 µm. The chip size is 6.4 mm by 6.0 mm. The bubble material used is (YSm)3(FeGa)5O12 with a demagnetized strip width of 4.5 µm. The chip is mounted in a memory module and tested by a chip tester at a rotating field frequency of 100 kHz. Complete memory operations are successfully performed using all memory addresses of all minor loops and an overall bias margin of 10% is obtained. Thus, the feasibility of practical 64 kbit memory chip operation is confirmed.