Don't forget, back in the day, chemists did a lot of scary things... smoking over whatever experiments, touching their samples, smelling and yes even tasting them(!)...
Tim
Was just browsing (insomnia) chapter 9 and I think that credit for the "two-transistor" bandgap voltage reference topology that doubles as an error amplifier as used in the LM317 ("Anatomy of a 317", page 604 and figure 9.13 page 606) has been wrongly attributed to Widlar-Dobkin.
To date I was of the understanding that this bandgap topology is originally attributable to Paul Brokaw, as detailed in:
A Simple Three-Terminal IC Bandgap Reference, IEEE JOURNAL OF SOLID-STATE CIRCUITS,VOL.SC-9,NO. 6, DECEMBER 1974
I have attached a pdf of this document. Note that this paper references the paper by Widlar mentioned in chapter 9 (ref#14 page 604):
New Developments in IC Voltage Regulators, IEEE JOURNAL OF SOLID-STATE CIRCUITS,VOL. SC-6, NO 1, FEBRUARY 1971
For convenience, I have attached a pdf of this document also.
Brokaws paper begins with the "conventional bandgap circuit" as outlined by Widlar in the latter, and then builds upon the concept, describing the "new" combined reference and regulator topology that is topologically/functionally equivalent to figure 9.13 in AOE3.
AOE3 "Anatomy of a 317" states that the LM317 was designed by Widlar-Dobkin "around 1970" and gives ref#14. However, ref#14 doesn't actually detail the LM317 circuit shown in fig 9.13, but that of the LM109 fixed 5-V linear regulator, which uses a somewhat different variation of the "conventional bandgap circuit" (as far as I can currently see now at 1.22 am).
It would still be nice to know exactly when the LM317 was designed, but I suspect it wasn't before the Brokaw paper unless there was a highly coincidental/improbable independent development.
It's further stated in section 9.10.2 (page 679):
"The classic bandgap reference requires three transistors, two for delta-Vbe and a third to add a Vbe. However, Widlar and Dobkin cleverly created a two-transistor version, first used in the LM317, see Figure 9.13."
I think these sections in chapter 9 need to be re-written for the next printing to give correct credit to Brokaw for the "two-transistor" bandgap reference:
I'll go back and look at my references, and yours, but first, let's say I believe its pretty clear Bob Widlar invented the classic three-transistor Vbe reference.
And he either invented the two-transistor version, or knew about it very early.
**The ISSCC used to be held each year in Philadelphia, and I always went, at least until about 1972, when I started my company and became too busy. Furthermore the ISSCC moved to the west coast, too far for me to travel. One year, maybe it was 1969, maybe a year or two later, I was exiting an auditorium mid-session to move to a different session, and I came across Bob Widlar and Bob Dobkin standing alone outside. (In those days Dobkin was always a Widlar look-alike with his beard.) At the time I was quite excited about the new Vbe reference circuit and praised it to Widlar. His answer was that it could be done with two transistors, could I see how? That took me back and I couldn't think of how, or any answer, so the conversation ended early.**
I think perhaps what Widlar didn't do, was write about it first.
As much as I love my hardback copy, I'd love it if this were available as an ebook. It definitely makes reading it in bed, or in a cafe easier. You shoudl see the looks I get when I lug the hardcover edition into a cafe at 8am on a Saturday morning (to compare, my wife is usually carrying her kindle )
Great Job Paul!
I Thank You for the effort and time it took to put this together. Not asking to much can a Excel version be exported to Excel?
After four months of effort we've got a first draft of a monster index; we'll be cleaning it up, adding plenty more terms, etc., but if you want to see it in its current 50-page form, there's a link on the main page, at
http://artofelectronics.net/wp-content/uploads/2016/06/subject_index_8jun16.pdf
suggestions happily accepted -- please send them to me at horowitz@physics.harvard.edu
paul
"This page intentionally left blank" ... ?
(Sorry)
"This page intentionally left blank" ... ?
(Sorry)Taking user notes, probably. It's probably a way to store your important notes inside the book itself.