H*****l
发帖数: 702 | 1 i could
a-si/c-si is junction interface----silicon heterojunction solar cell
a-si brings you high Ef difference, passivation on surface ( so no need on
diffusion) and still reasonable light transport
a-si is low temp process so no need to go to 800 for diffusion or anealing
and a-si dep is very fast since it is only 10-20 nm for a-si emitter/
passivator
the interest lies on " how to make efficiency from 200 degree process as
high as traditional 800-1000 degree process"
is |
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w**t
发帖数: 592 | 2 电路:
sensor -> comparator(5v 几十uA)-> ?电路(提高驱动电流) ->负载
负载的输入电阻比较低，我的电路只能输出几十uA量级的电流。一旦连上负载电压
立刻从５v降到１v，什么电路可以加到中间提高输出驱动电流(只要能提高到几mA就好)？要求这个驱动电路只能用Vcc=５v。
试过BJT的emitter follower，我的电路甚至连基极都无法驱动。也试过FET,OP AMP的
voltage follower,输出电压都只是１v多点。还有什么别的办法？ |
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a******t
发帖数: 75 | 3 假设Gate或者base voltage是固定的，source或者emitter是ground。
如果是silicon BJT，temperature cofficient 是 positive,温度上升，beta上升，Ib
减小,rb (base resistance) 上的压降减小，BE junction voltage增加，所以Ic增加。
如果是GaAs 或者SiGe HBT, 因为温度系数是negative，所以Ic会减小。
如果是MoS,明显温度上升，电流减小。因为mobility 和 Vth 都随着温度升高而降低，
但是mobility是最主要的因素，所以Id电流减小。 |
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a******t
发帖数: 75 | 4 temp factor positive 只是对于silicon BJT而言。 对于GaAs 或者SiGe的BJT来说是
negative.
在高功率电路设计中，这两种device的blasting reisitor 的加法是不同的。一个在
base，一个在emitter。 |
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l****o
发帖数: 184 | 5 我觉得出现2rpi1是因为在q1的emitter不仅仅有q1的1/gm,还要串联上q2的1/gm，这样
就有两个1/gm了。 |
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C*********Q
发帖数: 348 | 6
没有完全看懂你的分析。 如果MN3没有turn on, MP1/2/3的gate高，Q1
的colletor高，emitter低，Q1turn on，pull downMP1/2/3，MP2 will charge the
gate of MN3, plus nmos current mirror will pull down MN3'source. MN3 would
be turned on.
btw, 如果没有MN1/2/3和MP3，这个电路好像还是能工作？
解决问题的关键是让MP1/ |
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c********r
发帖数: 172 | 7 1. For Q1 to turn on, it requires its Vbe>0.7V, Vce>0 is not the condition
for Q1 to turn on. So if its base voltage cannot rise up, it will never turn
on
2. Without MN1/2/3 and MP3, there is no feedback loop for the band-gap to
start up
：没有完全看懂你的分析。 如果MN3没有turn on, MP1/2/3的gate高，Q1
：的colletor高，emitter低，Q1turn on，pull downMP1/2/3，MP2 will charge the
：gate of MN3, plus nmos current mirror will pull down MN3'source. MN3 would
：be turned on.
：btw, 如果没有MN1/2/3和MP3，这个电路好像还是能工作？ |
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C*********Q
发帖数: 348 | 8 Vx = 2*Vbe， base of Q1/0 is one vbe down, then it is about Vbe. if there is
no current in R1 or R0, the emitter of Q1/0 is 0 and they are turned on.
I don't understand how MN3 helps for star up.
turn
the
would |
|
s**g
发帖数: 66 | 9 Thank you for sharing.Your discussion is very informing.
I'd like to make a few comments:
1. is MP0 a JFET? If so, the device symbol you drew is incorrect.
2. Almost all band gap start up ckt can be properly simulated. That is, you
shall be able to predict if the ckt could latch up to off-condition. Keep in
mind start up problem is essentially a DC operating point problem, not a
transient issue.I guess you either use transient sim or power supply DC
sweep to verify your design, which is not the ... 阅读全帖 |
|
c********r
发帖数: 172 | 10
MP0就是一个PMOS管子
shall be able to predict if the ckt could latch up to off-condition. Keep in
mind start up problem is essentially a DC operating point problem, not a
transient issue.I guess you either use transient sim or power supply DC
sweep to verify your design, which is not the right way to do it.
并不是所有的启动都可以完全正确地仿真出来。像这个旧的band-gap电路所有corner的
仿真都显示没有start-up issue，但就这两块芯片在这里出问题了。
另外，当启动电路只有两个DC工作点时（其中一个是零电流状态），你说的是对的，就
是一个工作点问题，只要避开零状态点就可以。当启动电路有多个DC工作点时（你估计
没有遇到过，但我遇到过），就很复杂了。
启动过程必须用瞬态仿真来验... 阅读全帖 |
|
e********h
发帖数: 12 | 11
MP1/
这个bandgap的启动电路应该是Q2，所以Q2会拉高Q1Q0的base从而启动电路，这个电路
应该不会有启动问题。有可能是X或者Q2的emitter电压过低，导致无法启动。但是这个
电路有个设计问题，Q2这个启动电路无法停止工作，如果Q2的电压过高，会导致
bandgap两路mismatch，从而增加TC。 |
|
C*********Q
发帖数: 348 | 12
没有完全看懂你的分析。 如果MN3没有turn on, MP1/2/3的gate高，Q1
的colletor高，emitter低，Q1turn on，pull downMP1/2/3，MP2 will charge the
gate of MN3, plus nmos current mirror will pull down MN3'source. MN3 would
be turned on.
btw, 如果没有MN1/2/3和MP3，这个电路好像还是能工作？
解决问题的关键是让MP1/ |
|
c********r
发帖数: 172 | 13 1. For Q1 to turn on, it requires its Vbe>0.7V, Vce>0 is not the condition
for Q1 to turn on. So if its base voltage cannot rise up, it will never turn
on
2. Without MN1/2/3 and MP3, there is no feedback loop for the band-gap to
start up
：没有完全看懂你的分析。 如果MN3没有turn on, MP1/2/3的gate高，Q1
：的colletor高，emitter低，Q1turn on，pull downMP1/2/3，MP2 will charge the
：gate of MN3, plus nmos current mirror will pull down MN3'source. MN3 would
：be turned on.
：btw, 如果没有MN1/2/3和MP3，这个电路好像还是能工作？ |
|
C*********Q
发帖数: 348 | 14 Vx = 2*Vbe， base of Q1/0 is one vbe down, then it is about Vbe. if there is
no current in R1 or R0, the emitter of Q1/0 is 0 and they are turned on.
I don't understand how MN3 helps for star up.
turn
the
would |
|
s**g
发帖数: 66 | 15 Thank you for sharing.Your discussion is very informing.
I'd like to make a few comments:
1. is MP0 a JFET? If so, the device symbol you drew is incorrect.
2. Almost all band gap start up ckt can be properly simulated. That is, you
shall be able to predict if the ckt could latch up to off-condition. Keep in
mind start up problem is essentially a DC operating point problem, not a
transient issue.I guess you either use transient sim or power supply DC
sweep to verify your design, which is not the ... 阅读全帖 |
|
c********r
发帖数: 172 | 16
MP0就是一个PMOS管子
shall be able to predict if the ckt could latch up to off-condition. Keep in
mind start up problem is essentially a DC operating point problem, not a
transient issue.I guess you either use transient sim or power supply DC
sweep to verify your design, which is not the right way to do it.
并不是所有的启动都可以完全正确地仿真出来。像这个旧的band-gap电路所有corner的
仿真都显示没有start-up issue，但就这两块芯片在这里出问题了。
另外，当启动电路只有两个DC工作点时（其中一个是零电流状态），你说的是对的，就
是一个工作点问题，只要避开零状态点就可以。当启动电路有多个DC工作点时（你估计
没有遇到过，但我遇到过），就很复杂了。
启动过程必须用瞬态仿真来验... 阅读全帖 |
|
e********h
发帖数: 12 | 17
MP1/
这个bandgap的启动电路应该是Q2，所以Q2会拉高Q1Q0的base从而启动电路，这个电路
应该不会有启动问题。有可能是X或者Q2的emitter电压过低，导致无法启动。但是这个
电路有个设计问题，Q2这个启动电路无法停止工作，如果Q2的电压过高，会导致
bandgap两路mismatch，从而增加TC。 |
|
K**********n
发帖数: 1197 | 18 学术界珍稀有限的原版外文资料，
Remote Mind Control Technology
Reprinted from SECRET AND SUPPRESSED: BANNED IDEAS AND HIDDEN
HISTORY, edited by Jim Keith, $12.95, available from
1-800-680-INET.
There had been an ongoing controversy over health effects of electromagnetic
fields (EMF) for years (e.g., extremely low frequency radiation and the
Navy's Project Seafarer; emissions of high power lines and video display
terminals; radar and other military and industrial sources of radio
frequencies and micr... 阅读全帖 |
|
m********g
发帖数: 21 | 19 二级管的turn-on voltage和做这个二级管的材料有关。从材料可以大概判断这个器件
turn-on voltage理论上大概的范围。
GaN led（blue，green emittion） 的turn on voltage 一般不可能低于2.5V。如果IV
找不到明显的拐点从现有的信息判断我想大概有两种可能。1. 这个器件没有形成有效
的pn结，只是个resistor。2.你的电压还不够，很多情况下器件真正的turn on
voltage比理论值高，因为有contact resistance等factors，实验室里的作出的器件比
理论值高个两三倍都有可能。 |
|
m*******9
发帖数: 77 | 20 女生，机械工程PhD, 有材料工程的minor， summer毕业，求内推。
专业偏向微制造，半导体，微流体测量， CAD, 和ANSYS模拟. 有MEMS超净室，微器件
设计，模拟和制作的经验。
做过的project包括：MEMS infrared photonic crystal emitter, microfluidic
chip design and measurement, micro-scale surface treatment and
characterization (AFM).还有ANSYS模拟MEMS energy harvest。
现在正辛苦寻找Entry Level位置，感觉没有工作经验，还是十分不容易啊。有过几个
面试，都因为需要sponsorship没有下文了。
不挑工作和地点和报酬，希望各位大侠能帮忙内推或提供机会，感激不尽。
请站内联系……
谢谢了！！！ |
|
R****i
发帖数: 2387 | 21 Technical Physics, vol. 50, issue 7, p. 944
Effect of Screening on the Emissivity of Field Electron Emitters Based on
Carbon Nanotubes
我这里不知怎么搞得，就是issue 7没有。
谢谢。
如果有的话，mail至r****[email protected] |
|
M*********m
发帖数: 2024 | 22 为什么GaN的HBT不好呢？GaN作emitter应该提供了一个更高的电压阶越，电子输运应该
更像ballistic transport啊。。。。 |
|
w********o
发帖数: 10088 | 23 GaN做collector倒是可以借助high breakdown的优点
说道ballistic，在GaN里面好像得25nm以下，生长上没啥问题，关键是process。
nitride没有好的selective wet etching的方法，用干法etch 25nm 范围控制起来应该
困难。要不就regrow emitter，我觉得regrowth也是很没谱的事情，做研究还行。。。
而且p-type的nitride总是让人头疼。。。我感觉InGaAsP这个系列是做speed device的
很好的平台，InSb那个系列做speed nano device挺好，nitride和他们拼speed不合适 |
|
m********r
发帖数: 811 | 24 Minimum Opening Angle
Consider a particle beam of emittance (=phase space area occupied by the
beam) 4.8 mm*mrad. In a collider, this beam is compressed to a half-width of
44 micrometers. What is the minimum opening angle (half-divergence) in
degrees of the beam at the collision point? |
|
m********r
发帖数: 811 | 25 Minimum Opening Angle
Consider a particle beam of emittance (=phase space area occupied by the
beam) 4.8 mm*mrad. In a collider, this beam is compressed to a half-width of
44 micrometers. What is the minimum opening angle (half-divergence) in
degrees of the beam at the collision point?
The minimum opening angle is achieved using rectangular phase space |
|
x********4
发帖数: 97 | 26 第一次在这里发帖，想请版上的大牛帮我查一篇paper。
title: Experimental evidence of direct contact formation for the current
transport in silver thick film metallized silicon emitters
J. Appl. Phys. 110, 114511 (2011); doi:10.1063/1.3665718 (5 pages)
如果能下载到全文，请发到我的站内信箱，非常感谢！ |
|
g***u
发帖数: 22 | 27 Use a blade and a 1-D precise positioner and a power metter. Put the power
meter behand the blade which is mounted on the positioner. Move the postioner,
measure the the Power as a function of position, fitted with cummulative
guassian funcion
it |
|
g***u
发帖数: 22 | 28 elliptical beam is simply a guanssin beam that has different x waist and y
waist. Do the suggested experiment at the same location in two ( may be three
) different orentations, you can fit the beam profile at that point.
postioner,
Is |
|
w*******y
发帖数: 60932 | 29 Another price drop. Link:
http://www.amazon.com/Marantz-SR8002-Surround-Receiver/dp/B000X18Y7C
Here are some specs.
125 Watts x 7 Channels All Discrete Amplifier Stage
Current Feedback Amplificatio n
HDMI v1.3a Repeating/Switching: 4-In/2-Out
DolbyTrueHD, DolbyDigital Plus, dts-HD Master Audio
Deep Color, xvYCC and SA-CD Support by HDMI
Up-Conversion (w/TBC) to HDMI with 480i/480p Converter
Assignable Dual Component Outputs
M-DAX (Marantz Dynamic Audio eXpander) for Compressed Audio
HD-Radio
X... 阅读全帖 |
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w*******y
发帖数: 60932 | 30 Panasonic TC-46PGT24 Plasma, 1080p, 3D, THX + 1 pair 3D glasses, $899.99 +
tax costco.com
Tax is on the pre-instant mfr. rebate; was $90 in MI (6%). Store pick-up is
free or shipping is $29.99.
I'd been looking for this exact TV only to learn, so I thought, that there
was no 46" in the GT line. I'm glad to be wrong! The 46" is made for the
warehouse stores: Costco, Sams Club, etc.
For the price of a 46" G25 plus tax ($904 at amazon with free shipping and
no tax), one can get the addition of b... 阅读全帖 |
|
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w*******y
发帖数: 60932 | 32 Just saw this on www.mp3pla.net:
http://www.mp3pla.net
Amazon has The 99 Most Essential Gregorian Chants:
http://www.amazon.com/dp/B004UJ6XEY/
MP3 Album for $1.99
Tracks
1. In Paradisum - Liturgia Dei Defunti E Dei Santi: Clamaverunt Iusti
2. In Paradisum - Liturgia Dei Defunti E Dei Santi: Requiem Aeternam
3. In Paradisum - Liturgia Dei Defunti E Dei Santi: Dies Irae
4. In Paradisum - Liturgia Dei Defunti E Dei Santi: De Profundis
5. In Paradisum - Liturgia Dei Defunti E Dei Santi: ... 阅读全帖 |
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w*******y
发帖数: 60932 | 33 Vann's has the Mitsubishi 60" 1080p 3D rear-projection DLP HDTV WD60738 (
Black) for $569.88 with free shipping and no tax for most. Must add to cart
to see final price.
Link:
http://www.vanns.com/shop/servlet/item/features/458930053/mitsu
Comparison Specifications
Screen size: 60" (measured diagonally)
Display type: Rear-projection DLP
Aspect ratio: 16:9
Lamp: 156W and 180W modes
Progressive features: 3D-capable display / Stream TV Internet Media / Smooth
120 technology
Best video inputs: 3 HDM... 阅读全帖 |
|
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w*******y
发帖数: 60932 | 35 Saw this at urlhasbeenblockeds. Anyone knows how good is this flashlight?
link:
http://www.shophde.com/j58.html
ShopHDE has the CREE Q5 LED Flashlight for $9.95 - $4.20 off with coupon
code bensep145s44 [Exp 10/6] = $5.75 with free shipping. Features adjustable
focus, Cree Q5 SMD style LED emitter, and 800 meter range. Shipping is from
U.S. and is free for all orders.
It takes 3 AAA.
|
|
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w*******y
发帖数: 60932 | 37 http://http://www.tigerdirect.com/applications/SearchTools/item 80201&Sku=M402-7336 RF [tigerdirect.com]
List Price:$2,699.96
Instant Savings:- $1,700.00 (63%)
Price: $999.96 with Free Shipping today!
Mitsubishi 73" 3D DLP HDTV
Imagine watching action-packed scenes on an enormous display with an
amazingly picture and outstanding audio quality, with a drink in one hand
and popcorn in the other - while sitting in your own couch. Welcome to the
Mitsubishi 73" 3D DLP HDTV. Featuring its enormous 7... 阅读全帖 |
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w*******y
发帖数: 60932 | 38 Mitsubishi Cinema WD92840 92-inch 1080p 120Hz 3D DLP HDTV for $2888.00:
http://iway.org/9611371
add to cart for $2888.00 + Free Shipping (Offered Paul's Tv) (Price shown at
checkout)
3D TV
2D + Depth
Internal 3D Glasses IR Emitter
DLP Link 3D Glasses Compatible
Mitsubishi Exclusive 6 Color Processor
Plush 1080p Video Processing & Format Conversion
HDMI Deep Color (36-Bit)
PerfectColor & PerfecTint
Clear Contrast Screen
Video Noise Reduction
Picture Format Modes (4:3 sources): 6
Picture Format Mo... 阅读全帖 |
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f****w
发帖数: 947 | 39 Electrical Engineering. Ph.D. in 2000. Develop novel solid state detectors and
emitters. Low frequency noise in wide band gap semiconductor devices. 8
publications. 5 Recommendation letters. EB-2 NIW.
Molecular Biology. Ph.D. in 2001. Perform research in the complex areas
molecular therapeutics and intelligent small drug design to improve the
nation’s understanding, diagnosis and treatment of deadly disease, like
cancer and aids. 11 publications. 6 recommendation letters. EB-2 NIW.
Electrical an |
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