Characteristics of a bubble generator at high temperatures

Generation current margin is found to be limited not only by minimum current but also by maximum current. The generator maximum current I Gmax is measured for a 64 Kbit bubble memory chip with a 3 micron bubble. The chip temperature range was from 0 °C to 70 °C. A considerable loss of current margin is found at high current and high temperatures. This is considered to result from the generation of extra bubbles. I Gmax and its decay are observed to strongly depend on the shape of the generation pulse. A properly selected pulse shape increases I Gmax by 100 mA for a margin decay of less than -4 mA/decade and generate operation becomes possible in wide temperature range without compensation. Design combinations of generator and transfer gate or generator and replicator are proposed to give a more reliable generator port.