Recent content by djhuber82

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    What's with GSM cell phones and ticking sound into radios, speakers etc?

    GSM uses TDM: time domain modulation. Basically, A GSM phone is allocated many small time slices when it is allowed to transmit. To save battery life, the phone turns off the power amp when it's not transmitting. The switching transients from this are what you hear through your computer...
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    Lenz's Law & Eddy Currents: Questions

    The thickness of the copper pipe (wall thickness, not pipe diameter) will affect the speed. Thicker copper means lower resistance, which causes the eddy currents to be more effective at slowing the magnet. The easiest way to show this effect is to get a larger diameter pipe that fits over the...
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    Looking for grad schools

    I'm an EE grad at UCLA. The big names here are in RF and analog IC design. I don't know any good power programs off the top of my head, but I would advise you to search the last couple years of ISSCC and JSSCC for Class D amps, DC-DC converters, etc to see what schools are publishing work in...
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    What causes alkaline batteries to leak?

    Mixing old and new batteries can cause the old ones to leak. Also could be due to overheating (e.g. leaving your maglite in the car on a hot day).
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    Should I use the Arithmetic or Geometric Mean?

    I'm fairly confident that when refering to means, the terms 'aithmetic' and 'geometric' are used in the same sense as they are when refering to sequences.
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    Building an electromagnetic gun of some sort

    I recently saw a very cool science science project that might qualify. Hold short (~4 feet) length of copper pipe vertically and drop a neodymium magnet through the center. Anyone here care to guess what will happen?
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    Inductance of a coplanar waveguide

    For something free, check out AppCAD (made by Agilent, the same company that makes the MUCH more powerful ADS). It's great for calculating Zo of various transmission line structures. Once you have Zo you can back calculate inductance using Zo = sqrt(L/C) and c=1/sqrt(LC), where L and C are...
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    RF transistors

    RF transistors are usually junction devices (BJTs or HBTs), not FETs. These transistors are better suited to building high speed amplifiers and other RF blocks due to a number of factors, including: more transconductance for a given bias current, better matching, and higher speed operation...
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    IC EDA tools

    Hmm... I use cadence IC design tools at school and they don't crash that often, but they do crash. If you're seeing lots of crashes it might have something to do with the system setup. I agree the GUIs are definately craptastic though. From what I here many designers in industry don't even...
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    How do smaller die sizes allow for better performance?

    1.6nm gate oxide THICKNESS, not gate length. I'm doing analog design so the clock rates aren't that high (~300MHz).
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    How do smaller die sizes allow for better performance?

    Not that far off, actually. Gate oxide thickness is 1.6nm for the 90nm process I'm working in.
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    .

    There's no reason an iterative filter shouldn't work just fine. I do not agree that a moving average (FIR filter) will be more accurate than an iterave one (IIR filter). You can design a good low pass filter with either one, but an IIR will use fastly fewer resources and introduce much less...
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    .

    A low-pass filter may work for your application, but it is NOT giving you a true mean, just a local mean. That said, I don't know why you would want a true mean, because after a sufficiently long time the mean will basically not respond at all to new input. With a LPF you can track the input.
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    Can some explain the difference between Digtal and Analog Circuits?

    Analog circuits operate on analog signals, which are real physical quantities such as voltage or current. Digital circuits operate on digital signals, which are abstractions of real physical quantities (i.e. 0-0.5V = "0", 0.5-1.0V = "1"). Digital circuits are great as long as you are only...
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    What exactly is light? And why is "the speed of light" considered to be fastest anything can move?

    to move at the speed of light a particle must have zero mass, or it would take infinite energy to accelerate it. photons meet this crtiterea. i'm not aware of anything else that does.