gwh@mongoose.ess.harris.com (03/30/91)
I recently came across a reference to shmoo plots in an ECL data book. Can
anyone tell what they are, how to read them, and what information they are
supposed to convey?
Thanks,
Greg Hoffman
gwh@mongoose.ess.harris.com
gwh@su59d.ess.harris.comlbechtle@uceng.UC.EDU (laurie bechtler) (03/30/91)
Easy...a shmoo plot is just a graphical representation of some kind of circuit condition versus two input variables. When I had a real job (as opposed to this grad school stuff) it was at a semiconductor manufacturer and we used them all the time. There are as many variations as you have variables. Example: make the x-axis the supply voltage, and the y-axis the '1' state voltage level. Pick an output criterion, say, does the circuit pass some specific functional test? Place an X everywhere on the plot that the circuit passes the test. You end up with some funny blob shape full of X's that shows you where (on that particular set of axes) the circuit functions. I think the name came from the old cartoon Li'l Abner...wasn't there a creature called a shmoo? I could be wrong. Anyway, just take a close look at the axis labeling and the test criteria for the graph points. You can also use more levels of description (0-9, say, or letters) to mark different levels of performance.
ferguson@maitai.SRC.Honeywell.COM (Dennis Ferguson) (03/31/91)
>Easy...a shmoo plot is just a graphical representation of some kind >of circuit condition versus two input variables. [stuff deleted] > >I think the name came from the old cartoon Li'l Abner...wasn't there >a creature called a shmoo? I could be wrong. [stuff deleted] Gee... I was taught that a smho was the reciprocal of resistance or what is formally called conductance. Hence, the smho was ohms spelled backwards. Several years back, the smho was abandoned for the internationally accepted term "Siemans". This was comparable to the abandoning of "cycles per second" for "Hertz". Is there some joke here I'm not getting.... Dennis
mcovingt@athena.cs.uga.edu (Michael A. Covington) (04/01/91)
In article <1991Mar30.171137.25052@src.honeywell.com> ferguson@maitai.SRC.Honeywell.COM (Dennis Ferguson) writes: >>Easy...a shmoo plot is just a graphical representation of some kind >>of circuit condition versus two input variables. [stuff deleted] >>I think the name came from the old cartoon Li'l Abner...wasn't there >>a creature called a shmoo? I could be wrong. [stuff deleted] > >Gee... I was taught that a smho was the reciprocal of resistance or >what is formally called conductance. Hence, the smho was ohms spelled >backwards. Several years back, the smho was abandoned for the internationally >accepted term "Siemans". This was comparable to the abandoning of "cycles >per second" for "Hertz". > >Is there some joke here I'm not getting.... > Yes. A reciprocal ohm used to be called a "mho" (never "smho") and anyhow "smho" is not "shmoo" (look closely at the order of letters in it). The mho is now called the Siemens (not "Siemans"). -- ------------------------------------------------------- Michael A. Covington | Artificial Intelligence Programs The University of Georgia | Athens, GA 30602 U.S.A. -------------------------------------------------------