Recent content by daudaudaudau

Couldn't agree more! The worst textbook I have ever read. As one amazon reviewer put it: "The prose is both laconic and imprecise - a combination that spells very poor readability." I think Ashcroft and Mermin is great. It has lots of good explanations and actually tries to give you some...

Actually this particular derivation in Ashcroft and Mermin doesn't include any generation in the depletion region, but anyway you're right that the formula does make sense when thinking about a reverse biased diode. If we let ##p_{no}## denote the equilibrium density of holes on the N side, and...

##n_i^2## is the intrinsic carrier concentration, which doesn't depend on ##N_a## or ##N_d##, so how could that affect the result?

Hi. I'm trying to understand how the current in a PN junction depends on various parameters. I have found this formula in Ashcroft and Mermin. It looks like the current will increase if we decrease the density of donors and/or acceptors, Na and Nd. Is this correct?

Thanks. How would that look in spherical coordinates ?

Hi. I was looking for a chain rule in vector calculus for taking the gradient of a function such as f(A), where A is a vector and f is a scalar function. I found the following expression on wikipedia, but I don't understand it. It's taking the gradient of f, and applying that to A, and then...

In Sedra&Smith's microelectronic circuits they have the following expression for the drain current in a MOSFET in saturation iD = 1/2µpCox(W/L)Vov2(1+VDS/VA)But I don't see how this can be correct. Wikipedia also has another expression, see...

Hello. We learn that an NMOS is in the triode region for Vds < Vgs - Vth, and in this case the drain current has a given expression. My question is, is this also valid for Vds < 0 ? What happens in this case?

Well, clearly the depletion region is not infinite in extent. Also, the field is not constant in the figure that you said looks good.

Well the depletion region is a dipole, isn't it? So the e-field will look like this http://hyperphysics.phy-astr.gsu.edu/hbase/electric/imgele/edip2.gif So if the field is negative "inside" the dipole, it is positive outside (but of small magnitude, of course).

Hello. I have a question regarding the p-n junction. When I look at figure B here: http://en.wikipedia.org/wiki/P-n_junction it looks completely wrong to me. Take the E-field. It is going to be positive outside the depletion region, which in turn will make the voltage tend towards zero...

What about making a filter, that has the same transfer function as the noise spectral density and then passing white noise through this filter? So if the spectral density is flat, you just get white noise again, if the filter is 1/f you get more low frequency content and less high frequency, and...

Hello. Say I have a given noise spectral density and I want to plot the random noise signal arising from this spectral density in the time domain. How can I generally accomplish this? For white noise, I would just pull numbers from a normal distribution, but I don't know what to do for non-white...

Hello everyone. I'm working on a project where I have to do a finite element simulation of low frequency magnetic coupling. But my problem is that I don't know the permeability of all the objects involved. Can anyone suggest a good way to measure the permeability of these objects ? The objects...

I need it because the sharp current peaks (dI/dt) are creating magnetic fields which are inducing noise in a magnetic field sensor I have.