Random comments on common errors in technical documents

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MarcelvdG

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Joined 2003
DF96 said:
Possibly. I think UK EEs generally extend 'linear' to include 'affine', as 'affine' is not a word which crops up often on EE courses here. 'Linear' is taken to mean 'no new frequency components in the output'.

Interestingly, the strict definition of linear excludes all sources (e.g. DC PSU, AC oscillators) so may be mathematically correct but perhaps unhelpful?
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Strictly speaking, if there is no DC at the input but there is DC at the output, you have a new frequency component namely 0 Hz.

Anyway, an affine circuit can usually be split into a linear circuit and a bunch of independent sources. Superposition applies to the linear circuit, so you can turn on each independent source in turn and add the resulting output signals. I don't see what's the problem with that.
 
scott wurcer

scott wurcer

R.I.P
Joined 2004
MarcelvdG said:
-In the context of current feedback op-amps it applies to the exact same feedback configuration as normal voltage feedback (shunt at the output, series at the input), but with an op-amp having a low open-loop input impedance at its negative input.
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IMHO this captures very poorly one fundamental property of CF op-amps, the closed loop BW to the first order does not change with gain. If the closed loop equations are rearranged to isolate the current into the inverting input things are very clear by considering that that current as what is fed back.
 
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MarcelvdG

Member
Joined 2003
Hi Scott,

I'm not denying that having a low open-loop input impedance at the negative input can have practical advantages, such as the one you just explained. All I'm saying is that three totally different feedback configurations are all referred to as "current feedback" because the term has been redefined at least twice. That doesn't make it any easier to understand what is meant.

Best regards,
Marcel
 
Shaun

Shaun

Member
Joined 2001
elipse.co.za
Pano said:
And the worst one of all, the eternal "And I" mistake. Seems that so few people in America can get that one right that it's going to have to change. Stupid, but that's the way it is. It seems we have a generation or two of English teachers that has failed us.

"And I" or "And me" - how hard can it be?
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Let's explore that. When do you use the one or the other? I do believe that we have been taught to use "and I" at all costs.

The way I figure it out is use whatever you would have used had the other person(s) not been included.

Jack and I went to the shop. (I went to the shop)
The shopkeeper stared at Jack and me. (The shopkeeper stared at me)
Not Quickly he handed the goods to Jack and I. (Quickly he handed the goods to I)

Also, I've never been told this or read it anywhere (that I'm aware of), but I believe the correct form is to refer to yourself last (not "me and Jack").
 
D

DF96

R.I.P.
Joined 2007
myweb.tiscali.co.uk/g8hqp/
Don't believe everything you read on the web. The Collins English Dictionary (2nd ed, 1986) says
"refute: to prove (a statement, theory, charge etc.) of (a person) to be false or incorrect; disprove.
"Usage: Refute is often used incorrectly as a synonym of Deny. In careful usage, however, to deny something is to state that it is untrue; to refute something is to assemble evidence in order to prove it untrue: 'all he could do was deny the allegations since he was unable to refute them'. "
 
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