Re: Not one single person has answered my MC1530 posting correctly

It looked too much like work, for way too little money.

I used to play chess, too, until I realized that one should always be paid for thinking.

John

Izzat when you joined Mensa ?:-)

...Jim Thompson

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|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
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I love to cook with wine.      Sometimes I even put it in the food.

No, that's when I joined this newsgroup.

John

LOL ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
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|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

Hmmph. I posted the correct answer to this on Saturday, but nobody seemed to notice.

--
Rick

I guess that slipped by me since it's numeric rather than a general Algebraic solution. But it looks correct.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

That was from the Auton-Bell-Rick consortium of multiple personality- purely blind arithmetic with no insight whatsoever- a worthless response.

Yes.

I was hoping to convey some analytic thinking, but to no avail :-(

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

Oh yeah- and this "YD" character also posts under the name ChaosMaster- aren't we lucky to have him. YD means Yellow Dirtball or Yankee Detester , take your pick.

I am not exactly sure- but in the case of subcircuits like that Q9/Q10, you may be relying on emitter area ratios to set some of the bias currents. Then Q3-Q4-Q5 is another transcendental. The circuit is tough.

notice.

Q9/Q10 relied on 1:1 area. One year into production without problem, the device was moved into the new Motorola process building "P". Yield went to hell on a handbasket. The problem resolved to offset issues between Q9/Q10. I simply removed 100ohms from R10 and placed

100ohms in each emitter. Problem solved.

Q3-Q4-Q5 run at essentially the same current, so tracking error is second order.

And this was the good ol' days... this was all breadboarded first.

I don't know that the circuit is "tough", it is simple-minded, but subtle; everything about IC's is transcendental ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

I read in sci.electronics.design that Fred Bloggs wrote (in ) about 'Not one single person has answered my MC1530 posting correctly', on Wed, 21 Jan 2004:

That's what I like about you, Fred. You're all heart.

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PLEASE do NOT copy news posts to me by E-MAIL!

God how awful - the object of the excercise was to determine the output voltage of a relatively simple op-amp, and that's exactly what I - and only I - did. Didn't spot your insightful response anywhere.

--
Rick

Jim - did you not look at my post - it should be fairly evident that I MUST have understood and analysed the circuit in order to be able to provide this numerical answer. If you'd wanted purely algebraic responses, then why include the component values?

--
Rick

Q9/Q10 are, you dimwit, a current mirror. There are newborns who know that the currents in a current mirror scale with the ratio of the emitter areas.

It is neither transcental nor tough.

Q4/Q5/R5/R9 set the voltage on the base of Q3, which defines its emitter voltage and hence the current through R3. This current is the bias current for the long-tail pair. Was that sufficiently non-numerical for you?

Still not enough? Let's go through it piecemeal:

1. Determine current through Q4/Q5: I = (Vee - 2*Vbe) / (R5/R9)
2. Determine voltage on base of Q3: Vb = I*R5 + 2*Vbe
3. Determine voltage on emitter of Q3: Ve = Vb - Vbe
4. Determine current through R3 and hence Q3: Ibias = Ve / R3 = (R5 * (Vee - 2*Vbe)/(R9 + R5) + Vbe) / R3

--
Rick

Of course you did, I just prefer an Algebraic solution... numerically doesn't help the silent lurkers with understanding.

I'll leave the values out next time, and make it an exercise for the student to optimize the circuit performance ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

Good idea. Just thought I'd add that to some of us, the dissection of an op-amp at the discrete level is new stuff. 3 or more pairs of current mirrors, biased and matched is an interesting concept, and all the math in the world is not going to discribe the logic behind how it works or what it is doing. There is some info on how these work at the bottom of

however. So not everyone is as smart[ass] as Rick. Some of us need the newborn, non-numerical, piecemeal equivalents. Some of us are also not solely electrical engineers, or particularly fond of math. (Re: Albert Einstein.) Shoot, some of us have a hard time remembering what day it is. :)

[snip]

Tom Frederiksen's book is a very good tutorial (if you can find a copy)...

"Intuitive IC Op Amps" National's Semiconductor Technology Series © 1984

No ISBN

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

Mark - the newborn stuff was just a swipe at Mr Bloggs who clearly didn't understand the circuit - or even its bias, for crying out loud - but who still felt the need to denigrate me, even though I was the only one to demonstrate the correct answer.

--
Rick