ST面向手持设备的MEMS解决方案- 意法半导体厂商_在线座谈

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主题：ST面向手持设备的MEMS解决方案
在线问答：
[主持人：ChinaECNet]	各位听众（网友），上午好！欢迎参加中电网在线座谈。今天，我们有幸邀请到ST公司的专家就“ST面向手持设备的MEMS解决方案”举行在线座谈。在座谈中，您可就您关心的问题与ST公司的专家在线进行直接、实时的对话交流。中电网衷心希望通过大家的共同努力，不仅能够增进各位听众（网友）对“ST面向手持设备的MEMS解决方案”的了解和掌握，而且能够为大家事业的发展带来裨益。	[2007-5-17 10:22:27]
[主持人：ChinaECNet]	我们已经进入问答阶段如果听众想重温演讲或内容可以点击下面“回顾演示”重看演讲。	[2007-5-17 10:46:02]
[问：flyman135]	在PDA上應用MEMS技術,工藝上有什麼嚴格的要求?layout是否有走線要求?
[答：SeakChuan]	Yes, For MEMS accelerometer, please follow guideline as below: 1. It is recommended not to place vias / through holes neither underneath the sensor nor at distances less than 2 mm from the sensor. 2. Trace connected to pads should be as much symmetric as possible. Symmetry and balance for pad connection will minimize component rotation. 3. To attenuate high frequency noise, it is recommend the use of 100nF ceramic or polyester capacitor which must be placed as close as possible to device Vdd lead. For filtering lower frequency noise, a large aluminum capacitor of 10μF or greater should be placed near device in parallel to former capacitor. 4. It is recommended to mount the sensor as close as possible to the center of mass of the object/system to be test to eliminate any centripetal acceleration sensed, if the object rotates during the fall. If the accelerometer is not mounted at the center of mass, the total acceleration during free fall will be non zero, and equal ?2R, where ? is the angular velocity in radiant per second, and R is the distance between the sensor and the center of mass. This suggestion is important for small device which is subject to rotations while falling.	[2007-5-17 10:48:56]
[问：dongqiwei]	为什么蘑菇形结构能提高温度的稳定性
[答：SeakChuan]	With the old structure, we have five anchor points which join the substrate and sensor. The temperature for example: from right side to left side may have different temperature reading, this temperature will affect 0g offset and sensitivity. With new structure, we have only one point in the center, distribution of temperature sense will be evenly spread to sensor.	[2007-5-17 10:55:21]
[问：ykh271828]	请问ST的加速度传感器集成了温度传感器吗？能否进行温度补偿之类的，还有就是除了温漂补偿还有哪些参数需要校正？
[答：Brown]	没有集成温度传感器，ST的加速度传感器温度平均漂移< 1 mg/degree.C，部分器件的温度平均漂移< 0.mg/degree.C,因此不需要进行温度补偿。 ST的加速度传感器在出厂之前都会进行校正，原则上客户不需要自己校正，如果客户有特殊的应用，要求很高的精度，可以对零g的输出值以及灵敏度进行校正。	[2007-5-17 10:55:38]
[问：sincereding]	ST基于MEMS技术的传感器可以分为以下四种：MEMS动作传感器，MEMS压力传感器，MEMS射频器件，MEMS微流体器件请问这几种传感器的精度，抗干扰指数？
[答：Hongshao]	MEMS射频器件 and MEMS微流体器 still under development. The detail spec and launching schedule are not known yet. For the accuracy of MEMS动作传感器, different device has different range of accuracy. For analog output device, ST defines xxV/g or equivalent. For digital output device, ST defines xxbit/g. For example, LIS3L02AL define Vdd/5 (V/G). For LIS3LV02DQ, the sensitivity is 1024bit/G. For MEMS压力传感器, ST uses xxmV/bar to define. For example, The sensitivity for LPS400CL is 70mV/bar. The detail are listed in the datasheet.	[2007-5-17 11:00:11]
[问：alexzheng]	二维的MEMS产品的能否在汽车上应用来检测汽车的前进和后退?,二维和三维产品在价格上有多少优势?
[答：Brown]	二维的MEMS可以检测汽车的前进和后退，二维一般比三维的便宜20%-40%.	[2007-5-17 11:00:29]
[问：yuehm]	你好,这种低成本的传感器能为手机带来什么技术上的革命呢?
[答：SeakChuan]	For MEMS linear accelerometer in mobile phone application, it can be used for antitheft, GPS dead reckoning, gaming, digital compass, menu/photo browsing, Pedometer and etc...	[2007-5-17 11:02:52]
[问：flyman135]	應用到MEMS技術,數據值是怎樣校準的?
[答：Hongshao]	In ST production, the calibration of the MEMS is by using a precision industrial standard testing fixture. The equipment compares the difference of MEMS output and provide the data to configure the internal OFFSET and GAIN controller of the MEMS	[2007-5-17 11:05:43]
[问：royalyuan]	曾经听过Freescale公司关于加速度传感器的报告会，不知道ST公司的加速度传感器产品同Freescale的有什么自己的特色
[答：Brown]	应该是各有各的特色，就现阶段来讲，我所知道的是ST的产品系列比较齐全，有模拟和数字输出接口的加速度传感器，至于具体的技术规格差异，用户可以下载datasheet做一个比较。	[2007-5-17 11:05:59]
[问：ltyyl]	mems 的可靠性是如何保障 mems 在医疗领域的应用
[答：SeakChuan]	1.For MEMS accelerometer, we have a stopper to limit the miximum movement of sensor mass, this ensure to withstand high shock like 10,000g in 0.1 milisecond impact duration. We also perform strictly reliability test in ST factory. 2.In Medical Area, it can be used for fitness monitoring like pedometer, blood pressure meter.	[2007-5-17 11:08:56]
[问：alexzheng]	我比较感兴趣的是MEMS的动作传感器(线性加速计/陀螺仪)可以在汽车防盗系统上的应用,但是现在世面上的大部分防盗器使用的是类似压电片来代替动作传感器,就是利用检测声音来实现震动检测,也能起到一定的效果,我就想了解一下ST的MEMS动作传感器在这方面有没有应用,有什么优势所在?
[答：Hongshao]	压电片only provide the vibration detection. The application of MEMS in automotive alarm provides not only vibration detection. It provides the vehicle tilt or pitch angle information to the system. The system is able to detect the vehicle is being tow away or being broken into.	[2007-5-17 11:09:53]
[问：flyman135]	对于手持设备，PDA怎样辨别用户手持的水平轴的变化？比如计步时，用户是否必须保持一个轴方向运动，XYZ轴的运动方向改变，是否计数OK？
[答：Hongshao]	ST R&D has developed an algorithm for pedometer for some other Japan customers. By using 3 axis MEMS, user don’t have to tie the portable device to a particular position.	[2007-5-17 11:12:40]
[问：sduboy]	ST的MEMS传感器在检测震动和自由降落时其灵敏度如何？
[答：SeakChuan]	It depends on which device, ST has analog and digital MEMS. For analog, sensitivy is 660mV/g. For digital, sensitivity is 1024bit/g. ST MEMS has high freefall accuracy and ST MEMS is widely used for branded Notebook maker in the market for harddisk protection during vibration as well as free fall event.	[2007-5-17 11:13:41]
[问：justflyahead]	请问何時需用2D MEMS加速器,何時需用3D MEMS加速器?謝謝!
[答：Brown]	需要用到3D加速器的应用主要有： 1.硬盘跌落以及震动保护（笔记本电脑，带硬盘的PDA,手机） 2.计步器，使用3轴的加速器有更好的精度 3.GPS辅助导航 4.3D游戏 5.需要用到运动轨迹识别的应用，比如机器人，MEMS鼠标等等	[2007-5-17 11:16:21]
[问：alexzheng]	MEMS产品能否实现多传感器的串联,最多能连多少个MEMS传感器?
[答：Hongshao]	If I am not misunderstood you, your intention is to use more than one MEMS in one system. Am I right? Use analog output MEMS as example. The number of MEMS using in one system is no limited. Depends on how many A/D port you are assigning for MEMS.	[2007-5-17 11:18:16]
[问：orwellsheng]	MEMS对动态和静态的方位测试有什么不同啊
[答：SeakChuan]	ST 3 axis digital MEMS integrate low pass filter as well as high pass filter. During dynamic control, you can turn on high pass filter for Shake/Vibration/Wake up detect. This will help to bypass DC component. For static control like tilt/freefall/portrait-landscape switch, you should not turn on high pass filter. Low pass filter will reject hih frequency noise.	[2007-5-17 11:20:38]
[问：lulu2890]	装在手机中计步器是采用那种类型的MEMS?是2D还是3D?
[答：Brown]	计步器采用加速度传感器，有使用2轴的也有使用3轴的，3轴的计步可以更加精确，如果是主推计步器概念的手机，建议使用3轴的加速度传感器。	[2007-5-17 11:22:30]
[问：whappin]	MEMS射频器件使用MEMS技术实现低功耗,高稳定性,这种稳定性如何来保证呢?谢谢!
[答：SeakChuan]	ST do not have RF MEMS in the moment. I am not able to commend on this.	[2007-5-17 11:22:45]
[问：zgjswxwf]	数据表中的"Offset can be eliminated by enabling the built-in high pass filter (HPF)"是漂移补偿吗?如果是,是温漂还是时漂?如果不是,烦请说明,谢谢!
[答：Hongshao]	When high-pass-filter is turned on, the DC level of the MEMS is utilized to 0. Therefore, "Offset can be eliminated by enabling the built-in high pass filter (HPF)". I must highlight that this is not a compensation. Using hardware engineer point of view to understand this behavior is: serial a capacitor on the output. Therefore, only AC can pass through. The DC measured at the output point is 0.	[2007-5-17 11:23:21]
[主持人：ChinaECNet]	各位观众，现在用户提问很踊跃，专家正在逐一回答。请耐心等待您问题的答案，同一问题请不要多次提交。	[2007-5-17 11:24:48]
[问：leenet]	What are the most important features we should consider when the MEMSs are used for portable devices?
[答：SeakChuan]	Key factors are listed as below: 1. Low power comsuption to save battery life. 2. Wider operation voltage like 2.16V to 3.6V 3. Good sensitivity 4. Good 0g offset 5. Good temperature stability.	[2007-5-17 11:26:07]
[问：kingsea]	电容式MEMS开关如何仿真？绝缘介质膜如何设置？
[答：SeakChuan]	Company confidential, sorry for not able to anwer your query.	[2007-5-17 11:28:49]
[问：huangsongtao2001]	ST的MEMS有那几种类型?各用在那里?
[答：Brown]	现阶段ST的MEMS主要是加速度传感器，后续会有陀螺仪以及MEMS麦克风。加速度传感器可以使用在笔记本电脑，游戏机，手机，PDA，GPS，洗衣机，测量仪器。	[2007-5-17 11:33:11]
[问：zgjswxwf]	请问怎么用加速度传感器来测倾斜?假设又倾斜又振动的前提下如何测倾斜?在全温度范围内精度有多少?
[答：Hongshao]	1. To measure the tilt or pitch, you can use this equation as a reference. : Angel=arcSin(Gx/G). Where: Gx is the sensed acceleration on X axis. G is the gravity of the earth. 2. During vibration period, the vibration is affecting the value of the actual angel also. The angel measurement is not accurate. 3. Use LIS3L02AL as example, tolerance along the full temperature range from -40’C ~ 85’C is +/-0.5mg/’C with regarding to +25’C.	[2007-5-17 11:35:12]
[问：kingsea]	贵公司如何保证MEMS传感器的稳定性？
[答：SeakChuan]	In sensor design, we have stopper to limit maximum sensor movement that withstand high shock at 10,000g at 0.1msec duration. In ST factory, we also perform strictly reliability test. The reliabilty is gurantee in our specification.	[2007-5-17 11:38:02]
[问：shulinpeng]	ADC是12位的，噪声如何？根据Datasheet 提供的指标，在6g的条件下使用，300Lsb/g 就是说10mg的加速度变化只有3个Lsb 的变化，那么实际使用中分辨率就大打折扣了，那么，如何低成本提高加速度的分辨率呢？
[答：Hongshao]	To increase the measurement accuracy, one of the method is by data processing. But you must give up some response time for the calculation. The simplest approach to minimize the affect of noise is by calculating the MEAN (average): Reade 4 or 8 or even 16 ~ 32 times from MEMS, sum up the value and divide by the number of readings. The reason to measure 2^n time is for the sake of simpler calculation for the MCUs.	[2007-5-17 11:42:46]
[问：shulinpeng]	我不明白MEMS在手机或相机中对浏览图片的自动设置优势，有更廉价的传感器可以实现的，请解释一下。
[答：SeakChuan]	Browsing/ photo portrait-landscape is only few feature suggested. You can use MEMS for many other features suggested from the presentation material. These features may not be able to use traditional cheap sensor to implement it.	[2007-5-17 11:43:22]
[问：justflyahead]	ST的MEMS加速度传感器的分辨率和频响如何？
[答：Hongshao]	Use LIS3L02AL as example, the resolution is Vdd/5 (V/G). The response bandwidth is 1.5KHz with 1nF output filtering capacitor.	[2007-5-17 11:45:45]
[问：linghz]	MEMS需要校准吗?如何对MEMS进行校准?出厂后的校准如何进行?
[答：SeakChuan]	ST MEMS are 100% calibrated for sensitivity and 0-g offset before shipment. Ingeneral, it does not require further calibration at customers site, unlike some other competitors.	[2007-5-17 11:46:21]
[问：glnunu]	数字输出与模拟输出的优势及各自的使用范围？
[答：Brown]	数字输出和模拟输出最大的不同点就是数字输出内置A/D转换，输出的信号是I2C或者SPI的，而模拟的是没有内置A/D转换的，输出的信号就是与加速度成正比的电压值，用户需要使用外接的A/D转换芯片对模拟信号进行转换。当然，数字输出芯片的价格比模拟的要贵一些，但会低于模拟输出＋A/D转换芯片的价格，数字的因为内置了A/D转换而且有中断信号输出，可以降低功耗。	[2007-5-17 11:48:45]
[问：shulinpeng]	我们想使用MEMS来辅助汽车在高架桥或隧道中的导航，该使用二维器件还是三维器件呢?
[答：Brown]	应该使用3维的MEMS器件。	[2007-5-17 11:49:58]
[问：alexzheng]	MEMS动作传感器X,Y位移数据输出的格式是怎么样的? 请推荐几款对应的MPU产品?
[答：Hongshao]	I used ST74F264 and ST7Lite before. Anyway, the output format is configurable for ST’s digital MEMS to suite all type of MPU. For LIS3LV02DQ, please see BLE bit and DAS bit detail description in CTRL_REG2 (21h).	[2007-5-17 11:51:20]
[问：huangsongtao2001]	MEMS在硬盘中的保护功能是如何进行的?响应时间有多快?
[答：SeakChuan]	In harddisk protection, we can use for shock/vibration( > threshold setting e.g. >100mg) and for freefall protection (<threhold setting e.g <350mg). The response timing for sensor is very fast. ST already have many branded notebook maker use it for harddisk protection.	[2007-5-17 11:51:23]
[问：lig82]	一个性能良好的MEMS,至少要包括那几部分?
[答：SeakChuan]	good sensitivity. good 0g-offset. good temperature stability.	[2007-5-17 11:52:41]
[主持人：ChinaECNet]	由于时间关系，本次中电网“在线座谈”马上就要结束了。虽然各位听众（网友）已与ST公司的专家讨论了许多问题，但是还有许多提问没有来得及进行交流。本次在线座谈结束后，中电网将请ST公司的专家继续答复所有的来自各位听众（网友）的提问，然后整理上载到中电网网站上，以便大家查阅。	[2007-5-17 11:54:10]
[问：glnunu]	MEMS的测试非常重要，但又不可能将每个元件尽数测试，在这个问题上，ST是如何处理的？
[答：SeakChuan]	ST perform 100% calibration and testing before shipment. ST MEMS integrates self test feature to allow customer to check the fuctional of sensor in their production.	[2007-5-17 11:54:54]
[问：ykh271828]	关于ST的MEMS加速度计的带宽配置是通过何种方式实现的？
[答：Hongshao]	Use LIS3L02AL as example, bandwidth =1/(2PiRl*Cf) Where Pi is a constant 3.1415…. Rl is the internal loading resistor which is fixed at 110kOhm for LIS3L02AL Cf is the external filtering/loading capacitor which can be determined by user. For 1.5KHz response speed, 1nF is recommended.	[2007-5-17 11:57:38]
[主持人：ChinaECNet]	所有问题均已提交给ST公司的专家。座谈期间未回答的问题，ST公司专家也会逐一回答，并在中电网上公布，请大家注意收看。	[2007-5-17 11:58:02]
[主持人：ChinaECNet]	在此，中电网特别感谢给予本次中电网在线座谈巨大支持的ST公司，特别感谢专门在线回答各位听众（网友）提问的ST公司的各位专家们，特别感谢各位听众（网友）积极热情的参与。	[2007-5-17 11:58:30]
[问：bitter]	ST的3轴MEMS加速度传感器如LIS3L02AQ5和Freescale的MMA7260Q相比,有什么特点和优势?
[答：SeakChuan]	Please contact ST directly for the comparison table.	[2007-5-17 11:58:31]
[主持人：ChinaECNet]	祝大家事业有成、生活愉快！欢迎多提宝贵意见，欢迎关注中电网，下次再见。	[2007-5-17 11:58:40]

	涂学全 MEMS技术市场经理	1991年毕业于台湾国立大学电子工程专业。加入ST已有6年，目前担任MEMS技术市场经理，其主要职责在于在亚太区提供MEMS技术支持及高端应用支持、开发各种MEMS评估板及演示方案。同时涂学全在某些应用的研发和应用支持有着非常丰富的经验，如无线通信、LCD/CRT显示器、硬件驱动等等。
	陈鸿韶资深应用工程师	2001年毕业于新加坡南洋理工大学电子工程专业（硕士学位）。于2005年加入ST，目前担任资深应用工程师，主要负责电路设计及产品改进，如设计加速传感器的演示板及评估板的，包括ST模拟MEMS，LIS3LV02DL，LIS302DL等。此外，陈鸿韶在消费类产品和IT电子方面的硬件设计有着12年以上的丰富经验。

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