s*******y
发帖数: 4173 | 1 if possible, consider the differential input.
which can eliminate power supply noise. |
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t****7
发帖数: 471 | 2 我目前不在EE,有一个去搞noise radar的机会,但是都说雷达不好找工作,特别在美国,
对EE里电磁场方向的就业形势特别是雷达相关了解不多,希望大家指教 |
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s*******y
发帖数: 4173 | 3 我也不太懂，只做过一次，输入的你就选输入信号的
电压源，输出你就选输出信号。
有人说那个flicker noise的仿真结果不准，我觉得
这个东东还不如手算方便些，如果电路不复杂的话。 |
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H****E
发帖数: 444 | 5 请问我的hspice输出结果只有inoise和onoise，怎么才能看电流的noise呢？比如Sid？ |
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f*********t
发帖数: 37 | 6 Sometimes we assume the input of A/D is a white signal and has uniform disitribution between [-max +max]. This is just an assumption. According to this assumption, the quantization noise for each sample will be independent to each other with the same distribtion. Power spectrum of i.i.d random process is white. |
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f*********t
发帖数: 37 | 7 Not sure if it is related with 滤波器.
Because if the input of A/D is a sine wave, then the quantization noise won'
t be white no matter what filter you use. |
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le
发帖数: 190 | 8 I understand it's white. The input signal doesn't necessarily need to be
random, it just need to be busy.
I just don't see why its spectrum is from DC to fs/2. Of course, it cannot
be infinity, otherwise the PSD has to be zero.
disitribution between [-max +max]. This is just an assumption. According to
this assumption, the quantization noise for each sample will be independent
to each other with the same distribtion. Power spectrum of i.i.d random
process is white. |
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h********t
发帖数: 555 | 9 The original question is why quantization noise is band-limited to fs/2. what you claimed is that the power spectrum of the sampled signal from [-fs/2 fs/2] is the same as [(n-1)*fs/2 (n+1)fs/2]. In real world, that will not happen, because that could only happen if you could build an impulse sampling circuit. however, in real world, you just can not implement a impulse sampling circuit. you will have to either use sample and hold or sample and track circuit. in that case, the power spectrum of |
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h********t
发帖数: 555 | 10 The original question is why quantization noise is band limited to fs/2.what
you claimed is that the spectrum of the sampled data is band limited to fs/
2. From design aspect,as an approximation, we may assume that is true, but
strictly speaking, neither of them is really band limited to fs/2.
with ideal impulse sampling, for the sampled data, the high frequency
spectrum of the original signal will be aliased back to lower frequency,
but the lower frequency components will get high frequency |
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f*********t
发帖数: 37 | 11 Well, I was talking about perfect sampling. I guess the original question
was about perfect sampling. This is just my guess because this is an
assumption in many DSP books when no specific sampling methods are specified
.
After sampling, continuous signals are sampled to discrete signal. Discrete
signal has periodic power spectrum. Based on this, we usually only consider
the power spectrum of baseband discrete signal winthin one period which is [
-fs/2 fs/2]. So not only for noise but also for a |
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h********t
发帖数: 555 | 12 That is right. I do feel it is very diciffult to comnunicate with you.You need understand that the operation of quantization is different from sampling, and the sampling rate of FFT simulation is different from the sampling rate of the data converter under test. If you are interested in how to run FFT to see quantization noise spectrum beyond the data converter sampling rate fs, you can read the book of CMOS Mixed- Signal Circuit Design by Jake Baker. Simulation file and output spetrum are all t |
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f*********t
发帖数: 37 | 13 yeah its like
y(t) ---> y(n*Ts)+Q(n*Ts) and Q(n*Ts) is the quatization noise.
|
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H****E
发帖数: 444 | 14 比如，就一个电阻，加一个电流源，如何测出thermal noise的wave form？。。。
谢谢！ |
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H****E
发帖数: 444 | 15 why....
难道noise对digital circuit一点也不重要吗？。。。 |
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m*****o
发帖数: 6598 | 16 找到了吧。你在pdf下面搜noise,很快就有了，按照example做吧 |
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t*****m
发帖数: 254 | 17 括号内显示的是该信号的每单位赫兹的平均POWER。因为你设置的RBW是100KHZ，所以该
频率点的带宽是100KHZ，于是每赫兹的平均POWER要从显示的该点的POWER减去50DB。
noise |
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E****d
发帖数: 146 | 18 noise floor 大概-80 dbm的样子 |
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l******n
发帖数: 697 | 19 Hi all
Can anyone recommend a book on mixer noise analysis?
Thank you |
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l****o
发帖数: 184 | 20 如果你指的是mosfet 的corner frequency,那一般来说从几十Hz到几十kHz.但是output
noise frequency是取决于op amp的bandwidth。 我也觉得你概念混淆了
有具体的电路么？ |
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ET
发帖数: 10701 | 21 output noise current power spectre里的corner frequency是啥？ |
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s*****o
发帖数: 22187 | 22 I dont think Flicker corner can reach 10MHz level. Can you print the noise
summary from ADE?
you |
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R*****o
发帖数: 204 | 23 我想你是说，在flicker noise的实际测量中，由于测量仪器的limited bandwidth，
观察到的corner frequency比理论上的要高很多。
you |
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s*****o
发帖数: 22187 | 24 I guess so. If it's only one mosfet, input and output noise transfer is the
gain. And gain is flat at the freq we talk about. I cannot see anything
cause the fc drift. Please correct me if I am wrong. |
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s*****o
发帖数: 22187 | 25 I guess you are right. I only thought about the big size case for limiting
flicker noise. |
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s*****o
发帖数: 22187 | 26 想请教一下，如何仿真input-referred noise呢？以CS amp with R load为例，谢谢。 |
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s*****o
发帖数: 22187 | 27 Yes, I think so. But HighF said Fc is different for input and output noise.
So I want to learn how to simulate input referred Fc from him. |
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ET
发帖数: 10701 | 28 spice simulator会有个ｉｎｎｏｉｓｅ （ｌｔｓｐｉｃｅ)
ｓｐｅｃｔｒｅ应该也有类似的吧。
从ｉｎｏｉｓｅ曲线上和ｏｕｔｐｕｔ ｎｏｉｓｅ曲线一样。
自然能看到一个flicker noise corner..
. |
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s*****o
发帖数: 22187 | 29 可能还有考虑Cox的不同。我觉得最好的办法是看看他们的document，一般都有对flick
noise的测试结果。
flick
flicke
perfo |
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R*****o
发帖数: 204 | 30 嗯，很有道理
那么我想知道，一般的说，就好比是design一个LNA，我们知道channel length越小
的工艺，会提供更高的ft，因而会有更好的NF。那么对于design一个low frequency的
amplifier，flicker noise是不是也能得到同样的结论呢？
flick
flicke
perfo |
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ET
发帖数: 10701 | 31 为什么有更高的ft有更好的nf呢？
design for high speed, design for low noise本来也不同。 |
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s*****o
发帖数: 22187 | 32 According to Thomas Lee, Fmin=1+A*(f/ft), where Fmin is the minimum noise
figure. However, I dont understand why yet. |
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ET
发帖数: 10701 | 33 听起来应该没啥关系呀？
>1GHz, flicker noise 不用考虑了吧。 |
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ET
发帖数: 10701 | 34 baseband都用》1GHz了？
vco 还有flicker noise upconversion呢。
我们在讨论lna. |
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r*******r
发帖数: 1014 | 35 hehe, you know what I mean: 1/f needs to be considered in RF such as
baseband and pll.
so if we know the right objects:
(1) like vco, how to reduce/optimize 1/f?
(2) like adc (low quant-error such as sigma-delta), is device noise (1/f +
thermal) important to take care? |
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I***a
发帖数: 704 | 36 测SRAM static noise margin
画出butterfly curves 以后，maximum squares的大小是如何计算出来的呢？
谢谢。 |
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b**********g
发帖数: 141 | 37 比如说一个damped RC integrator，
R1 is between Vin and the negative input terminal of opamp.
R2 and C in paralled, between Vout and the negative input terminal of opamp.
请问R2的noise的contribution怎么算呢？
谢谢！ |
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s******u
发帖数: 142 | 38 What kind of topology you use in the divider? and what's the division ratio?
If the ratio is big, like 32, or 16, it'll be difficult to get the pss
converged. If division ratio is small, like 4, or 8, you can directly
simulate it like an oscillator.
and what's the spec for the Phase noise in your divider? |
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C*****y
发帖数: 203 | 39 Great. I am working on the /2 and /4 circuit. Someone was telling me that I
can not simulate the phase noise of the divider as the same way I do for VCO
because it is a driven circuit. That is the reason I am asking.
请大牛指教
ratio? |
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b*****g
发帖数: 269 | 40 关于noise分析方面的，还有jitter的
麻烦大牛推荐一本好的。多谢。 |
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f****3
发帖数: 502 | 41 据说phase noise的话hajimiri的书比较不错 |
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c*******m
发帖数: 522 | 42 我觉得是看你要保留的bits是多少了。一般quantization noise假设是一个uniform
distribution.数字信号的bits不一样，uniform distribution的variance也不一样。
你可以看下这个书Discrete-time signal processing
[PDF] from ketab.irAV Oppenheim, RW Schafer, JR Buck - 1989
希望有帮助。如果说得不对，还希望各位大牛拍砖 |
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w*******8
发帖数: 139 | 43 假设digital filter不会改变通带内的噪声与信号，那么带外的噪声衰减程度决定了你
可以用多少bits来表示最后的结果。一般输出的量化噪声不要大于原来的noise floor
和你希望的带外噪声水平.
不知对不对 |
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l******C
发帖数: 93 | 44 帅哥，专业点。。。没人会去copy paste去看图7的。
PLL本身就是一个low pass filter 特性，noise被也要被low pass filter shape |
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s********k
发帖数: 6180 | 45 有几个对LNA不是太清楚的地方：
1.不论LNA性能设计再好，也会放大receiving noise。
2.如果用了LNA之后，再刻意lower down TX power之后，Tx 的range会减低，但是
receiving range还有carrier sense range也同样降低吗？（整个link budget都降低
了） |
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j******s
发帖数: 17 | 46 个人感觉：
1. noise 会增加，所以NF对LNA很重要
2. receiving range/sensitivity应该是Rx的独立指标 |
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u*******m
发帖数: 3395 | 47 Basically LNA's gain suppresses the noise effects of later stages, thus
minimizes degradation of sensitivity. |
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s*********y
发帖数: 8 | 48 这是sampling过后的resistor的noise variance（i.e. resistor + switch + cap），
和这个问题不一样。 |
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s*********y
发帖数: 8 | 49 想起来abidi有篇paper可供参考，读了应该就很清楚了。
A. A. Abidi, “Phase Noise and Jitter in CMOS Ring Oscillators,” IEEE
Journal of Solid-State Circuits, vol. 41, no. 8, pp. 1803–1816, Aug. 2006. |
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m****a
发帖数: 132 | 50 【 以下文字转载自 EE 讨论区 】
发信人: muitta (muitta), 信区: EE
标 题: question on: Gaussian vs. uniform noise
发信站: BBS 未名空间站 (Wed Aug 1 22:06:15 2007)
想请教一下信号处理方面的问题。现有一些采样数据，如果在这些数据中加入Gaussian
或 Uniform 分布的噪声，然后再作 DCT 变换。假设这两种不同分布的噪声的平均值
以及方差都相同的化，请问它们对 DCT 的影响会有什么不同？ |
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