-
Sun Flower -- Provence
2008-03-23
-
太赫兹晶体管
2008-03-23
____________________________________________________
From compoundsemiconductor.net
It's the simple goals that tend to capture our imagination, such as the breaking of the four-minute mile and the first ascent of Everest. In our community we also have a similar goal – the building of the first semiconductor chip that can operate at 1 THz. This target is particularly interesting because it is being attacked on two fronts by strikingly different technologies. Quantum cascade lasers (QCLs) are making gains from the optical side as researchers build new structures to operate at longer wavelengths, while engineers are moving closer from the electronics domain with ever faster transistors.
In recent years, advances in transistor speed have been led by Milton Feng from the University of Illinois at Urbana Champaign (UIUC), who has raised his HBT's top speed to almost 800 GHz at room temperature. But he was pipped at the post in December when Richard Lai from Northrop Grumman Space Technology announced that his team's InP HEMTs had passed 1 THz.
Lai, the leader of the company's microelectronics products, reveals that his team has been working under the radar for the last few years, admitting: "This result is not something we focused on to achieve as a goal." Instead, the researchers have been aiming for the targets of a Sub-millimeter Wave Imaging Focal-plane Technology (SWIFT) program, funded by the US Defense Advanced Research Projects Agency (DARPA).
Northrop Grumman's role in this project is to build an amplifier operating at 340 GHz. But to provide amplification at this frequency, you need to produce transistors that are two to three times as fast, which explains why this team has been developing such high-speed devices. The researchers concentrated on characterizing the amplifier and only went on to measure their HEMT's speed when DARPA's program manager, Mark Rosker, asked if the researchers could claim a terahertz transistor. Measurements showed that this was the case and Lai was told to write this up and present the results, which he did at last December's International Electron Devices Meeting (IEDM).
The record-breaking speeds are the result of several modifications to Northrop Grumman's previous HEMT designs. Gate sizes have shrunk to 35 nm and adjustments have been made to the epistructure, including a switch to an InAs channel with very high mobility.
Northrop Grumman's approach to measuring the speed of its HEMTs reflects its target application – microwave devices. Here the key figure of merit is fmax, the frequency that produces a unitary power gain. Measuring this frequency with reasonable accuracy is a tricky task because it involves the extrapolation of data obtained at far lower frequencies (see box "Determining the speed of ultrafast transistors"). Lai accepts that extrapolation-based methods can undermine claims of terahertz records, but he counters this criticism by saying that all of the currently accepted methods for testing produce an fmax of more than 1 THz for his team's transistor. Applying the unilateral gain technique produced a value of 1.2 THz, and figures of 1.1 and 1.4 THz, respectively, were obtained by extrapolating maximum stable gain and making circuit model calculations.Lai claims that the ultimate validation for fmax extrapolation above 1 THz comes from the performance of the team's three-stage low-noise amplifiers that have also been built from these HEMTs. At IEDM he unveiled the results for a 0.65 × 0.35 mm MMIC chip, which can produce 21 dB of gain at 285 GHz, 18 dB at 300 GHz and 15 dB at 340 GHz. And he believes that amplifiers operating at much higher frequencies are also within his grasp. "We have devices with 1.4 THz fmax, so you should have some decent gain at 600 and 700 GHz. This is not our primary thrust but we are working on it." At these frequencies the difficulties are not associated with the chip itself but with the coupling of signals in and out of the transistors. Simulations have shown that this can be done, but his team is still to follow this up with a real demonstration.
Lai is also very keen to emphasize that his results are not just one-offs. "In industry my objective is not to try to demonstrate one terahertz transistor. This has to be a technology that can be manufactured, so yield and reliability are very important." Northrop Grumman has already produced tens to hundreds of wafers with this process and yields are encouraging. In particular, the process is producing T-gates with 99% yields that are also robust, according to temperature cycling and vibration tests.
One of Northrop Grumman's next steps will be the transition from prototype fabrication to genuine deployment. "We've got to get to the next level where we can make [our HEMTs] into blocks and start putting things together. We're still at the fundamental technology stage, trying to get the basic components and understand them."
Lai believes that the shipments of modules employing high-speed HEMTs for military applications, such as radar, will start on a very small scale. However, a lot of arrays will need to be built, and this could translate into substantial chip volumes.
From HEMTs to HBTs
Feng, meanwhile, has a very different application in mind for his high-speed HBTs – mixed circuits such as analog-to-digital converters. This application has a different key figure of merit, fT, the frequency at which current gain is equal to unity. (However, a high fmax is needed for a wide dynamic range.) At IEDM, Feng's team reported a speed of 683 GHz for its double-heterostructure HBT (DHBT), which increased to 745 GHz at –37 °C. "The device is not optimized," said Feng, "and we are expecting something even better to come out soon." He hopes that this structure can operate at more than 1 THz and believes that he can achieve that this year.Up until very recently, many of Feng's IEDM papers focused on the development of conventional single-heterostructure HBTs, but increasing the speed of these transistors has come at the penalty of a very low breakdown voltage. These devices could achieve terahertz operation at a marginal breakdown voltage, says Feng, but this is not good enough for mixed-signal applications. "In order to achieve [a breakdown voltage of] about 2 V in the terahertz regime, the technology requires the collector to be a larger bandgap," he added.
Switching to DHBT structures allows just this, and the UIUC team has been developing a type-II design that features a pure InP collector layer (figure 1). Feng claims that this is a superior structure to type-I versions, which have a transition layer in the collector section that causes current blocking. In comparison, type-II structures have a base layer with an energy band above the collector, which gives an advantage known as velocity overshoot. "Fundamentally, that gives you a fast transport through the collector," said Feng. His type-II designs also deliver better thermal conductivity, thanks to binary material in the collector, which is said to improve I-V characteristics and allow the HBT to operate at lower temperatures.
Like Lai and his team at Northrop Grumman, if Feng wants to make circuits that can operate close to 1 THz, he will have to build HBTs with top speeds that are way beyond that value. However, he thinks that will be possible with his current structure. "The problem right now is that we have a 400 or 350 nm emitter. If you look at silicon, it's 130 or 65 nm, but if we can get to that level we will cross over into the terahertz range."
One of the major players operating on the other side of the terahertz gap, and hoping to come down in frequency, is Jérôme Faist from the University of Neuchâtel, Switzerland. He and his team currently hold the record for the lowest frequency for a QCL, which stands at 1.2 THz for a GaAs/Al0.1Ga0.9As-based heterostructure. However, this laser can emit at just 850 GHz when a strong magnetic field is applied with a superconducting solenoid.
Richard：前段时间忽悠别人的时候提到了用InP HBT制作太赫兹器件和电路。看看，还在我么可望不可及之时，美国人已经捷足先登了。UIUC和Northrop Grumman，两边都是化合物半导体巨擘，同样也都有美国国防部的大单子。第一次听说了所谓QCL(Quantum Cascade Lasers)，不知道是什么东东。我们现在器件的频率，刚刚才追上人家电路的水平，看来距人家还有至少3dB呀。
MMIC chip, which can produce 21 dB of gain at 285 GHz, 18 dB at 300 GHz and 15 dB at 340 GHz.
____________________________________________________
-
Pico-projector
2008-03-21
____________________________________________________
想想，你的手机可以将其中的Pic或者PPT投影到墙壁上，是多么炫！这就是所谓的Pico-projector，即皮投影仪。早就听闻了Ti的DLP(Dynamic Light Projection)技术--已在Barcelona展出，但是迟迟没有产品推出。这是一个诱人的市场，可以由于成本的原因，还没有成熟到可以推到市场。不过，那个日子一定不远了。
说起光电技术，其实化合物半导体是很重要的角色。LED，光互连，激光--甚至激光驱动器，都有化合物半导体的影子。这个市场非常庞大，科研上前途也很光明，可惜呀--难言！
Luminus Devices' experience comes from its development of “Phlatlight” photonic crystal LEDs for the dynamic light projection (DLP) technology that Texas Instruments has developed. This technology has been proven in rear-projection TVs made by Samsung, for example (see related stories), and is being pushed for use in pico-projectors.
“The problem with the DLP is the cost,” explained Brennesholtz. “TI has been working on lower-cost DLP devices and they even showed one [at the Mobile World Congress] in Barcelona, but how low is low-priced? Nobody’s quite sure.”
The most prominent exponent of lasers for pico-projection is a company called Microvision, while an Israeli company called ExPlay is combining both lasers and LEDs.
____________________________________________________
-
RFMD研发“内幕”
2008-03-21
____________________________________________________
From: compoundsemiconductor.net
Vic Steel is looking to keep RFMD ahead of the rest of the GaAs field with MEMS for RF switch integration in handsets and an unexpected foray into photovoltaics. The company's vice-president of corporate R&D shares his game plan with Andy Extance.
Which is the single most important technology currently in development at RFMD?
Of course, I would say they're all important, so that's a hard question. I think our MEMS technology has the best potential to revolutionize several aspects of our next-generation systems, not just the RF switch.There are several ways that MEMS could change the way front-ends work. It could reduce all of the cellular power amplifiers (PAs) that might be in a multimode phone down to one PA with a load switch. The MEMS switches could allow one PA to be frequency-switched between bands, then switch between a linear mode and a saturated mode, allow for load changes and retain the optimum performance from the PA.
They can also allow other types of function. We've talked about the potential for adding resonators or sensors, such as accelerometers and gyroscopes, in the same technology that we're developing for RF switching. These functions can be implemented in a very low cost, incremental fashion.
When will we see the MEMS switches on the market and in what format?
The first implementation is going to be on CMOS because our initial concept is to put it directly on the driver circuitry for the switch. It will be a low-cost driver that supports the MEMS switch, which can then be applied in a module with our PAs or with other circuitry. Longer term this process can be integrated directly on GaAs as well, so it's really fairly flexible. It's still in development but we expect to release the MEMS technology for production next year.So, will MEMS be replacing PHEMT switches?
We believe it would be possible, yes. Initially we are focused on mode switching [between bands], which is currently done with PHEMT and is a slower process with fewer switching cycles than transmit-receive (TR) switching. We believe the MEMS technology that we're developing will have the lifetime to support TR switching as well, so in the longer term we could replace the PHEMT switch for both.What does this mean for the long-term future of GaAs at the company?
We see opportunities in the mobile phone area and other areas that we're addressing for compound semiconductors and silicon CMOS-based circuits for a long time. We don't see a transition from one to the other. We're beginning to pick up more CMOS, doing development and applying more of our efforts in silicon for various applications. That's not transitioning from our core competency in GaAs. You can see that obviously we're committed to our GaAs because of the capacity that's coming with the Filtronic deal.Why has RFMD been slower than other companies to use BiFET technologies?
We're working on BiFETs at the moment and we're well aware that our competitors have these on the market. We are really, really focused on what our customers' needs are. We felt that the technologies we had with HBT and PHEMT as separate die met the needs of our customers very well. We can see some applications as we move forward that will need BiFET technology, so we're developing it, but we didn't feel that it was something we had to have years ago, when they first appeared.There are some applications that can benefit from on-board control logic and bypass switching, so these types of applications are interesting. But full integration of a PA and a TR switch with decoding logic onto a single HBT or BiFET die? We're still not convinced about that direction for the transmit modules. We're going to have BiFET technology in some products, but as far as I'm aware we don't have a definitive plan to offer products that are fully integrated in that way, at least in the very near term.
Is RFMD really moving into photovoltaics?
We're actually quite excited about our opportunity in concentrator photovoltaics. From my perspective, this technology will have the biggest benefit to the use of photovoltaics in the end. We're actively pursuing that business area and I believe we have a good opportunity to have a significant impact on the availability of these high-efficiency concentrator photovoltaic cells. The way that we can address that market is by providing very large volumes at the lowest cost.Would RFMD's focus on MBE be a problem?
We agree that MBE is not widely used. We're evaluating it to make photovoltaic cells, but we're not depending on that. Whether MBE is the technology we use, or MOCVD, it's not going to affect our entry into the business.
About the author:Andy Extance is a reporter on Compound Semiconductor.Richard: 题目取“内幕”二字有些哗众以吸取眼球之意啊，呵呵。原来RFMD正在做MEMS和光电，看来是雄心勃勃呀。终于知道为什么在BiFET上，RFMD姗姗来迟了。嗯，感觉RFMD确实比较高明，follow the customer's needs，这是很多高科技企业所做不到或者说不情愿做的。技术至上，绝不是最佳的商业模式。RF MEMS在PA及TR中的应用是被广泛看好的，RFMD研发集团vice-president(如何翻译？)Vic Steel说道RFMD在保持在GaAs上的优势之时还正在加强Silicon的发展。再加上他们开始涉足光电产品，陆续收购，看来RFMD势头很足呀，祝RFMD好运！嗯，RFMD不错。
____________________________________________________
-
入川，再。
2008-03-15
____________________________________________________
明天，又去成都。这次和往次不同的是，这可能是最后一次为这个项目去了。已经记不清楚去了几次，待了多长时间。而取得多少收获，也是无从算起的。无论如何，那里留下一串串美好的回忆。喜欢成都，喜欢空气中散发的悠闲的味道，喜欢玉林小路上的树荫，喜欢两旁林立的小店，喜欢那里的人和味，只是不喜欢那里整天阴沉着的天空。
因为这个项目，我在有了一段在天上飞来飞去的日子，有了被打劫的痛苦，有了半夜被大雪困在海拔3000米的兴奋--这些都与交通工具相关。前两天李老师来的时候，去成都的机票只要360，可惜这几天没有这么便宜了。只好坐旅途漫长的T7--想起首次入川的时候，呵呵，那时候还是个不经事的胖子，现在瘦了十几公斤了。
希望一切顺利。
***
今天见识了传说中的VC，知道了一个叫做QIBJT（Quasi-Intrinsic Bipolar Junction Transistor）的东西和它在RFPA方向的“优势”。其实，因为材料太少，我又从来没有听过，所以，这里必须谨慎地打引号。如果真如他所说，在保证相似的线性度和效率及输出功率的话，由于他Si工艺基础的低成本和与CMOS易集成的优势，应该是挺有市场的。可惜，信息严重不足--Google/Baidu/SearchMash/ViviSimo都几乎没有任何收获，所以不敢妄下结论。无论如何，经一事总是有好处的，就像“开卷有益”这样的说法。
今天还见识了偷儿们的新招数，就在朝阳门外丰联广场。大街上有向你说话要求做调查问卷的--通常都是mm，那么此时你要小心你背后有人向你伸手了。一个吸引注意力，一个袭击，颇有声东击西的意味。我亲眼目睹整个过程，幸好当时那位女士五秒钟就摆脱了，否则恐怕我真会大打出手了，真是可恶。
***
上学期在清华大学选修的两门课，RF和Analog，都下了很多功夫。RF的成绩还是挺不错，刻蚀Analog的成绩，真是大跌眼镜，尽管也勉强可以算作高分了-比起大伙。想想上学期，几乎所有精力都花费在课程上面了，不知道是否值得，待日后检验吧。
***
这两天硬着头皮写国家自然科学基金的申请。看了两本UCSB的博士论文，发现他们写的真的很好，四个字：深入浅出。问题阐述的非常明了，论述和文字也很严谨统一，果然有牛校风范。UCSB的文件夹占用我的硬盘两年了，但我从来没有好好发掘，惭愧！
EndNote X!
____________________________________________________
-
TriQuint收购WJ Communications
2008-03-12
____________________________________________________
From: compoundsemiconductor.cnet
TriQuint to acquire WJ Communications for $72m
More GaAs consolidation on the cards, as WJ product innovation expands TriQuint's RF/Analog product portfolio and RF module capability
HILLSBORO, Ore.--(BUSINESS WIRE)--TriQuint Semiconductor (NASDAQ:TQNT), a leading RF supplier to the wireless communications industry and WJ Communications, Inc. (NASDAQ:WJCI), today announced a definitive agreement for TriQuint to acquire WJ. WJ is a leading supplier of radio frequency (RF) solutions for wireless infrastructure and will expand TriQuint's reach into this market.
Under the terms of the agreement, TriQuint will acquire by merger all outstanding shares of WJ for $1.00 per share, implying a purchase price of approximately $72 million. Excluding one-time charges, TriQuint expects the deal to be neutral to earnings during fiscal 2008 and accretive thereafter.
The transaction has been approved by the Board of Directors of both companies and is expected to close within 90 days, subject to an affirmative vote by WJ shareholders and other customary conditions.
Highlights of the acquisition are:
* Combines WJ design expertise with TriQuint's advanced technologies
* Expands TriQuint's presence in the communications infrastructure market
* Provides TriQuint with a Silicon Valley based design center
* Accelerates the evolution to multi-function modules for infrastructure applications
TriQuint has focused on bringing the technical innovation and cost savings it provides in the handset market to the evolving requirements of the communications infrastructure market. WJ shares TriQuint's vision of combining RF power, switching and filtering in cost effective module solutions for base station and other infrastructure applications.
"We see great synergy with TriQuint in the areas of technology, customer relationships and manufacturing efficiencies. There is very little product overlap and a good cultural fit between our two organizations," commented Bruce Diamond, CEO of WJ. "We bring a broad product line of RF building blocks and modules as well as a talented Silicon Valley based design team to an established leader in the RF market space."
Through this acquisition, TriQuint expects to expand its presence in the wireless infrastructure market comprised of cellular basestations and wireless and cable broadband infrastructure. "WJ's solid reputation in these market areas is a wonderful complement to TriQuint's strengths in design, manufacturing and customer support." said Ralph Quinsey, CEO of TriQuint.
"WJ's technical expertise combined with the financial strength and stability of TriQuint will provide both innovative products and security of supply to the networks infrastructure customer base."
Upon closing, it is anticipated that Bruce Diamond, CEO of WJ, will continue with the organization leading the business and assisting in integration.
Thomas Weisel Partners acted as exclusive financial advisor to WJ Communications on this transaction.Richard：哇塞！收购不断呀！再次赞前面有人预测的“四到五个Giants!”看来TriQuint动作频频，不断在拓展疆土。--72million美元？！
____________________________________________________
-
Optichron
2008-03-12
____________________________________________________
IIC-China 2008北京站，来捧场的公司太少了，大公司更少，远没有前年那么热闹了。不过还是发现了很感兴趣的东西。譬如说，美国Optichron，一个专门做PA的数字预失真（DPD：Digital Pre-Distortion）和峰值因素衰减（CFR：Crest Fator Reduction）芯片的小公司。他目前一共只推出两款芯片：OP5000和OP4400。关于PA的线性化，目前在无线通信领域中基本上都是用前馈和数字预失真，而前馈方案由于在输出功率上的优势所以占据叫数字预失真更大的市场。但是数字预失真技术的“数字化”，它正获得越来越多的应用。数字预失真的基本原理是用多项式来模拟PA的非线性，将数字的基带信号进行非线性处理，然后再送入PA发送。Optichron令人惊奇之处，在于它在研讨会上展示的几个应用了其DPD芯片OP4400的视频，PA的非线性明显降低，ACPR至少都提高25到30dB。
OP4400 -- Digital nonlinear signal processing
--- Modulation agnostic
--- Transmit architecture agnostic
--- Robust universal algorithm
--- No software development
--- Linearizes transmit path
OP4400与调制方式及发射器架构无关，也无需软件编程支持，可以直接用于使用各种PA技术的多载波WiMAX、GSM、CDMA2000、WCDMA和TD-SCDMA等系统。Optichron亚太区市场总监介绍，公司的创始人是做数学出身，他的算法高明之处在于并非采用多项式拟合PA非线性，这项技术并没有申请专利，看来核心技术只有一个人清楚。这么好的产品，我们都能看到一个非常广阔的市场--因为在IC产业，很少情况能够看到这么领先的技术了。可惜--我和师兄都有同感--他们的市场总监说话不大清楚。无论如何，是非常棒的技术！
OP4400 Performance：
OP4400 DPD Block Diagram
***
Steve C. Cripps的2nd Edition语言依然是那么艰涩难懂，但绝对是一本不可多得的经典之作。磕磕碰碰终于通读了一遍，献上读书笔记。
http://richard.blogbus.com/files/12052513260.pdf
***
李老师从成都过来，老板今天又忙于973解题，所以派师姐带领我们配李老师。中午在三苏饭店，不得不说那里的饭菜是我吃过的最好的，以至于只顾吃没有记下菜名来。怎么办？下次去的时候把整本菜谱都抄下来，嘿嘿！但是，那么贵，什么时候才能再去呢？
***
下午阿哲和中子拖我去打球，可惜晚上张丽和刘云要过来。好久没有上篮球场了，手痒痒。
想起黄胤给我写的大学毕业留言：“请记住我们在球场上驰骋的日子！”是的，我一辈子都不会忘记。
____________________________________________________
-
TriQuint
2008-03-11
_____________________________________________________
From eetchina.com
去年四季度，一场手机射频PA短缺的风波在中国漫延，瑞萨是这场PA短缺风波中的主角，因为联发科平台上主要采用了该公司的PA，据悉市场缺口达到了40%，部分PA在灰色市场被抄到原价的两倍；此外，用于3G手机，比如WCDMA/HSDPA的PA也出现全面告急，原因为主要供应商ANADIGICS没有预测到不同市场的终端设备同时出现对多个PA的需求，于是产能严重短缺。
“采用我们PA的用户不会出现这种情况。”TriQuint亚太区销售总监林伟仪对《国际电子商情》记者表示，“这正是越来越多的用户喜欢与我们合作的原因。”他解释道，TriQuint有丰富的产能，不仅他们自己的全部PA与滤波器、射频开关等都在自己工厂生产，而且他们还是全球很多PA芯片厂商的代工厂，比如TI和NXP的砷化镓产品都在TriQuint代工。“能为客户提供及时供货是我们非常大的优势。因为现在的终端市场变化很快，手机厂商很难准确的预测未来，芯片厂商很多时候需要满足手机厂商紧急的需求，中国市场尤其如此。”林伟仪表示。TriQuint目前在全球有两个砷化镓工厂，一个滤波器工厂。去年，它还被著名的调研公司Strategy Analytics评为“全球最大的商业化砷化镓代工厂”。
在本次IIC上，记者还获悉瑞萨与ANADIGICS在扩充自己产能的同时，也计划在今年部分外包生产，TriQuint则是他们重要的备选代工厂。今年，PA市场的需求增长仍会非常快，因为不论是手机，还是笔记本电脑、还是机顶盒，其中所需的PA数量都在增加。所以，今年全球的PA产能仍处于紧张状态。
TriQuint除了在供应及时方面受到中国用户的欢迎外，其为用户提供的高集成度模块也是备受青睐。它将PA与外围的开关或者双工器集成于一个封装非常小的模块中，为用户提供完整的射频前端模块方案。比如，他们为英飞凌的超低成本手机平台(ULC)优化的射频前端模块，集成了PA与天线开关，尺寸仅为7×4mm，“由于我们只取必要的功能集成，一方面保证了性能，另一方面可以做到很低的BOM成本，用户装配也很简单。”林伟仪表示。他们还有一款GSM发射模块集成了PA与开关，尺寸仅为6×6mm，用于中兴为沃达丰提供的超低成本手机中。
除了与英飞凌的GSM/GPRS平台配套外，TriQuint的PA也为高通的低成本CDMA手机平台配套。在为CDMA手机设计的射频模块中，PA与双工器集成在一起。“从集成策略上来看，GSM与CDMA有些不同。”林伟仪解释。
今年，TriQuint的GSM射频模块将会扩展到更多的平台上。“我们也在与MTK谈合作，事实上，市场上已有不少MTK的平台是采用我们的PA模块。”
而在3G方面，TriQuint的产品进程则显得比竞争对手比如ANADIGICS要慢一步。但是，林伟仪认为：“ANADIGICS只是关注于某一家公司(高通)的平台，而我们会与更多的平台配套。”他表示，在3G方面，TriQuint针对WCDMA/HSDPA的射频产品已面市，正在与博通、NXP、飞思卡尔、英飞凌以及高通等多家公司谈合作。“我们不会只关注于一个公司的平台。”他说道。明年，TriQuint将推出HSUPA的射频模块。
除去上面谈到的PA，TriQuint的SAW滤波器也不得不提，尤其是用于全球定位系统GPS的SAW滤波器。2007年，TriQuint向全球GPS设备厂商提供了总共5,200万个滤波器，其中包括全球四大PND制造商中的三家(根据Canalys调研公司数据)。从GPS SAW滤波器的出货记录看，TriQuint公司去年向世界领先的PND制造商提供了占其采用总量66%的SAW滤波器。
在此次IIC展会上，TriQuint发布了一款最新的GPS SAW滤波器。“和竞争产品相比，它能够在降低信号损耗的同时，更好的抵抗信号干扰，即同时具有低损耗和高阻带。这对GPS设备制造商来说是非常重要的特性。”林伟仪说道，“比如，在手机与GPS设备同时使用时，会有杂音，而采用我们的滤波器可以消除杂音。”他解释，在接受信号链中TriQuint SAW滤波器能够滤除非GPS信号源的其他噪音信号，同时降低GPS信号本身的损耗——这一过程保证了用于精准定位的所需数据得以顺利传输。
GPS设备与手机一样，同为增长最迅速的电子产品之一，此外还有机顶盒市场。TriQuint公司瞄准这些快速成长的市场，能提供高性能，高集成度和低成本的产品。我们认为，TriQuint的策略与其它射频公司的一个很大不同是，它非常关注于成熟的、量大的市场，并为这些市场提供性价比最好的方案，而这一策略恰恰对中国市场非常适用。
Richard: 原来TriQuint的产品线这么丰富，市场策略也很牛。
_____________________________________________________
-
我的大学四六级
2008-03-05
____________________________________________________
提起大学四六级，那自然想起我的大学--废话。USTC，留给我多少美好的回忆。所以，这篇要归为“心情故事”了。提起大学四六级，也自然想起，大学四六级，是关乎教父、土人和我的故事。
科大不允许大一学生靠四级--这是个奇怪的规定。所以，我的四级英语不是在科大考的，而是在合肥某个叫做“xx贸易学校”的中专考的--四级证书上盖的都是这个学校的章。记得，还有大个姜煊和我一起。这个家伙，现在在美国了，考四级都进考场了才发现没有带身份证，于是飞速打车回科大拿。幸好距离不是很远，来得及。四级真的没有什么难度，而且我们刚刚经过高考的锤炼，处于吃老本的前期阶段，所以基本上毫无准备就过去了。不过，也只是个及格而已，比起同班同学来，差得很远。那时候还不怎么认识教父和土人，所以四级和他们无关。
开始准备考六级，是大二下学期。当时和教父、土人关系已经很铁，大家是一起上的考场。当然，结果也都一样，因为我们一样都没有准备。大二下，尽管上大学也一直上英语，但是除了要准备出国的同学，大家的英语水平，嘿嘿，恐怕就像慢慢老去的老人。那个时候，我们组成了号称科大篮球历史上最正规的球队--Stop。无论是西区还是东区，篮球场上都留下了我们无数的汗水。夏天的时候，下午打过球，洗过澡，吃过饭，我们三个人喜欢在西区大门那里那块草坪上坐着，直到快要熄灯。年轻，无所谓，有无限多的精力供我们挥霍，怕什么？后来又一次准备考六级，我记得当时最怕词汇，所以买了一本依稀叫做《Smart词汇》的单词书开始背六级单词。那本书配有磁带朗读，所以也算是一本很不错的书。裸背一会，拿出磁带来听一会，效果居然还不错。而教父和土人，再一次裸考。所以结果是：我考了87，他俩又收藏了一张准考证。后来他们好像又考过一次或者两次六级，结果如何，我早就忘了--是呀，谁会真的很care这个呢？就让记忆和岁月一起被我们火葬吧，带走我们的青春年华。
郁闷的是，接下来再次考英语是考研的时候了，我考了很高的分数--到底多高记不得了；但是到研究生院的硕英免修考试，我居然挂了，真是不可思议。无论如何，硕英和博英总算都一次过关了。关于英语，接受最大的打击是在去年腊月。和两位业界的牛人一起聊天--当然是用英语了，我就摆尽丑态，不说也好，有些心痛。知耻而后勇--我总有话来为自己开脱的。
四六级证书好像都丢了。
____________________________________________________
-
Power Amplifier Design Issues & 鸟枪换炮
2008-03-05
____________________________________________________
再次表达一下对Steve C. Cripps的景仰，滔滔江水......最近抓紧时间研读他的第二版《RF Power Amplifiers for Wireless Communications》，很多原先比较模糊的概念变得清晰起来，可谓获益匪浅。写了几篇小小的读书笔记，仅仅是将人家的东西自己敲了一遍。分为几个不同的专题，这样做既使自己加深了映像，也可以备日后温习。好东西不可独享，放在这里抛砖引玉。希望对一些朋友用些用处，更希望高手们批评指正，大家共同进步。
1. 《功率放大器1dB压缩点与IIP3的关系》
2. 《功率放大器导通角波形分析》
3. 《HBT功率放大器设计中的偏置点选择》
4. 《功率放大器中的AM-PM效应》
5. 《功率放大器的过驱动与欠驱动》
6. 《功率放大器的热效应分析》
***
今天鸟枪换为大炮。早就受不了原先那台破Dell，每天数次不定时自动重启让我非常崩溃。运行ADS和Cadence犹如老牛爬山。上周终于对老板发飙，老板爽快地答应了我的刁难条件。没想到这么快，今天就拿到了。Dell Optiplex 755，配置非常不错，呵呵。不过，政府采购真够贵。
***
生活中不是缺少美，而是缺少发现。
--不信，
明天早起一点，出门呼吸点春天的新鲜空气，
你就会知道！
......
____________________________________________________
Complex Precision.
业精于勤
日历
湘南乃風- 純恋歌
|
|
水滴石穿
最新日志
最新评论
链接
- 访问统计：