Interview Question in analog circuits |
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analog circuits in electronics field
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Ok, I have this triode formula:
Gm = gm*(1/(1+ gmRs)
but I have no idea where it comes from...
I am a computer engineering student and I'm using the equation, but I honestly have no clue where it comes from... any ideas on a proof for it?
hope y'all can help me....
I'm just curious as to what brings forth this equation since I know
(d IDS)/(d VGS) = gm
and Vs = IDS*Rs
but there has to be a link between formulas
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One of my faves:
"The Art of Electronics", by Horowitz and Hill
This book is probably on the shelf of 95% of electrical engineers, who are electronic designers. It is a great all-around book for electronic design and it covers a lot of subjects very well.
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Other than noise-filtering, what is the purpose of a capacitor? It acts like a voltage source for a small amount of time. Can someone explain the uses of a capacitor, other than storing energy in an electric field. Explain in terms of capacitor's relevance in a circuit?
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I have started reading a robotics/micro-controller book, but have not reached the motor or digital to analog sections yet. From what I have read, I know the pins can output 0 to 5 volts, steady or at different pulse rates. Then theres digital to analog circuits, step motors, DC motors, AC motors, and infrared sensors that can read a pattern on the wheel and therefore calculate an angular velocity that can be used as feedback.
From all these tools, what is the typical method for controlling a motor's speed? What is the best motor to use? Should I drive it with pulses (PWM I think) or an anolog signal? Are there pins on some micro-controllers that can directly accept the analog signal from the infrared sensor?
I'm looking for a general explanation from somebody who has experience in building amatuer robots.
For your information, I'm looking to eventually buy A-Wits Technologies C-Stamp.
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Digital is more practical these days, as more and more circuits become more and more complex. Your iPod Nano has NO analog circuits in it, except for the headphone output and charging circuits (possibly). Analog is bulky, expensive (now) to produce, and limited. However, digital cannot exist without some sort of analog circuitry, either inside the chip itself (ie, IC) or on the board. You choose what you like. I take it that you are asking because you are confused on what classes to take? Probably it would be in your best interest to go digital. Everything is digital these days. However, if you ask me...analog is more fun.
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I am wondering how electrical circuits and systems are actually designed in the real world. Is there a formal process that goes into designing a circuit for a particular purpose? I have heard of electronic design automation for digital circuits, but how is this actually done? What about for analog circuits? Power systems? Thanks!
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A digital circuit is based on a small number of (usually
two) distinct voltage levels -- consider these high and low
or 0 and 1. Contrast this with analog circuits which are
based on a continuously variable signal.
The typical digital circuit has (conceptually at least)
two states, 0 and 1, and are designed using boolean
algebra (think AND, OR, NAND, NOT gates).
Contrast that with an analog circuit, which instead
of interpretting "high" voltages as "1" and "low"
voltages as "0", interpret voltages (at least
conceptually) as a floating point number.
The circuits have very different characteristics.
An analog signal often has some amount of signal
loss (think of the "hiss" from old analog phonograph
records), but they degrade gradually (ie. they
slowly get more and more noisy, but can often
still operate even with significant signal loss).
A digital circuit, however, will typically have
*no* noise because they often have error correction
built in to handle up to some threshold of signal
loss. However, at some point, rather than degrading
gradually, they just fail. Consider the difference
between the older-style cell phones (which would
sometimes get a little "noisy") vs. current digital
signal cell phones which are usually crystal clear
until they just "cut out". That's a common signature
of digital vs. analog processing.
For more discussion, see the wikipedia entries for
both "digital circuits" and "analog circuits".
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