闩锁效应起因？
参考答案：
由于寄生的可控硅效应引起CMOS电路的电源和地之间的短路，使CMOS集成电路失效。
防止latch-up的方法：
1、使N沟器件远离N阱，减小横向NPN管的b值；但会是芯片面积增大。
2、使Rnwell和Rpsubs尽量小；
使用尽量多的阱接触孔和衬底接触孔；
对于大电流器件使用保护环：
PMOS管周围加接电源的N+保护环；
NMOS管周围加接地的P+保护环；
大多数情况下，通过仔细地设计版图可以消除latch-up。
| 阅读短文，选择正确答案。 | ||
| Li Nan was born in Hangzhou, Zhejiang Province. Two years ago, he graduated from medical school at Zhejiang University. Then he volunteered to work with the Go West program. He went to Inner Mongolia Autonomous Region and worked as a doctor. At first, he worked very hard. But he felt lonely because he was a long way from home. Sometimes he felt feel like giving up. But after a short time, he was able to make many new friends. People there were kind and warm-hearted. He began to like the place. Li Nan has just completed his two years of volunteer service and returned home. He said, "I learned a lot. It was a useful experience for me." | ||
| 1. What did Li Nan do in Inner Mongolia? ______ | ||
[ ] | ||
| A. He went to university. B. He worked as a doctor. C. He worked as a teacher. | ||
| 2. How long has Li Nan worked as a volunteer in Inner Mongolia? | ||
[ ] | ||
| A. For four years. B. Since he graduated from Zhejiang University. C. Two years ago. | ||
| 3. Match the words on the left with their definitions on the right. | ||
[ ] | ||
| ||
| 4. What did Li Nan do after he completed his volunteer service? | ||
[ ] | ||
| A. He went back to Zhejiang. B. He stayed in Inner Mongolia. C. He went to university again. | ||
| 5. What did Li Nan think of his volunteer service? | ||
[ ] | ||
| A. It was lonely. B. It was hard. C. It was useful |