下一代无线网络架构

无线局域网(WLAN)技术为家庭和企业用户描绘了美好的蓝图,也吸引着众多半导体和系统设备厂商涌入这一市场。WLAN技术的不断演变,将标准制订团体、互操作性论坛(互操作性是市场进一步接受的关键要求)、产品OEM厂商和相应的半导体厂商紧密联系在一起。     

如何用硅振荡器替代晶体和陶瓷谐振器

对于绝大多数微控制器时钟电路而言，硅振荡器是一种简单且有效的解决方案。与晶体和陶瓷谐振器不同，基于硅材料的定时器具有抗振动、抗撞击和抗电磁干扰的优点。同时，硅振荡器不需要严格匹配的定时元件和线路板走线。     

A Built-in Self-Test Scheme with Diagnostics Support for Embedded SRAM

In this paper we propose a novel built-in self-test (BIST) design for embedded SRAM cores. Our contribution includes a compact and efficient BIST circuit with diagnosis support and an automatic diagnostic system. The diagnosis module of our BIST circuit can capture the error syndromes as well as fault locations for the purposes of repair and fault/failure analysis. In addition, our design provides programmability for custom March algorithms with lower hardware cost. The combination of the on-line programming mode and diagnostic system dramatically reduces the effort in design debugging and yield enhancement. We have designed and implemented test chips with our BIST design. Experimental results show that the area overhead of the proposed BIST design is only 2.4% for a 128 KB SRAM, and 0.65% for a 2 MB one.     

The effects of FG7142 on two types of forgetting in 18-day-old rats.

The authors studied the role of gamma-aminobutyric acid (GABA) in 2 types of forgetting of fear in the developing rat. One type of forgetting studied was that observed after an intermediate retention interval (the "Kamin effect"); the other type studied was that observed after a longer interval (infantile amnesia). Rats were given pairings of an auditory conditioned stimulus with shock, and learned fear was assessed by freezing. Forgetting at an intermediate retention interval (1 hr) was not alleviated by the GABAA receptor partial inverse agonist FG7142 (0, 1, 5, or 10 mg/kg), whereas forgetting at a longer retention interval (48 hr) was alleviated. These results suggest that in the developing rat, forgetting observed at different retention intervals is mediated by different physiological mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Opioid Receptors Regulate the Extinction of Pavlovian Fear Conditioning.

Rats received a single pairing of an auditory conditioned stimulus (CS) with a footshock unconditioned stimulus (US). The fear (freezing) that had accrued to the CS was then extinguished. Injection of naloxone prior to this extinction significantly impaired the development of extinction. This impairment was mediated by opioid receptors in the brain and was not observed when naloxone was injected after extinction training. Finally, an injection of naloxone on test failed to reinstate extinguished responding that had already accrued to the CS. These experiments show that opioid receptors regulate the development, but not the expression, of fear extinction and are discussed with reference to the roles of opioid receptors in US processing, memory, and appetitive motivation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

汽车电子系统要求低静态电流

如今的汽车电子系统越来越复杂。同时，汽车环境对任何电子产品来说都是很大的挑战，因为汽车电子系统要求运行电压很宽，并且有很大的瞬态电压和温度变化。另外，性能要求也越来越高，需要多个供应电压以满足系统的不同要求。典型的     

单片同步降压型转换器LTC3416

许多微处理器和数字信号处理器(DSP)需要一个核心电源和一个在启动期间必须进行排序的输入／输出(I／O)电源。如果未经过适当的电源排序，可能发生闭锁或过流，从而损害微处理器的I／O端口或诸如存储器、逻辑电路、现场可编程门阵列(FPGA)或数据转换器之类支持设备的I／O端口。为了确保在主电源电压未被适当偏置之前I／O负载不被驱动，对核心电源电压和I／O电源电压进行跟踪是必要的。