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Ironies of automation.

Now it has been lately quite some time trying to improve my page generation script, as well as having to fiddle around with some helper scripts at work that are supposed to make our life easier. By a coincidence last week I was visiting some friends in Sweden, from topic to topic, quite late in the evening I was recommended a paper title which appeared to be extremely entertaining to read.

It focuses on the ways in which automation tries to heal problems with human machine operators and the total man-hour labour efficiency when you draw the line accounting the time and complexity required to create the latter automation systems.

Further reading, on Bainbridge's webpage.

Date:Tue Apr 01 20:42:00 CEST 2014


A continuation of the content management script.

I have been fiddling a bit with my page content management script. So now except the pages I am also auto-generating the page bars too. As another field test I will just as well share the skeleton of my generator.

We first have the basic stuff:

 ############## EDIT THIS ###########################

/media/05022eeb-bcac-4484-8eb0-1b41d4eae750/site-tex-res/site-sync/ \

I.e. I look through the "post" folder and the html files in it and then build-up the pages by concatinating a base skeleton and the posts e.g.:

#declare -i cnt
#declare -i p


for f in $FILENAMES; do
for i in `find $DIRECTORIES -type f \( -iname "*$f*" ! -iname "*~" ! -iname ".*" \) | sort -V -r `; do

#flinedate=$(head -n 1 $i) #Auto file date fetch stuff, that is currently not implemented.
#echo $date

cnt=`expr $cnt + 1`

if  [ "$cnt" -lt 5 ] && [ "$p" -eq 0 ]
	cat $i >> $CATSTR

elif [ "$cnt" -lt 5 ] && [ "$p" -ne 0 ]
	cat $i >> $CATSTR

	p=`expr $p + 1`
	if [ "$dobase" -eq 0 ]
	echo $BASE >> $CATSTR

	cat $i >> $CATSTR



Then generate the pagebar:


for k in { 0..$p }; do # Generate bottom Page bar


	if [ $z -ne 0 ]
		echo "
Page: " >> $CATSTR for r in `seq 0 $p`;do olz=`expr $olz + 1` if [ "$olz" -eq 1 ] then echo "0  " >> $CATSTR else olzt=`expr $olz - 1` echo "$olzt  " >> $CATSTR fi done echo "
" >> $CATSTR echo "

Last edited: $DATE by $USER

" >> $CATSTR echo "\n" >> $CATSTR else olz=0 echo "
Page: " >> $MAININDEX for r in `seq 0 $p`;do olz=`expr $olz + 1` if [ "$olz" -eq 1 ] then echo "0  " >> $MAININDEX else olzt=`expr $olz - 1` echo "$olzt  " >> $MAININDEX fi done echo "
" >> $MAININDEX echo "

Last edited: $DATE by $USER

" >> $MAININDEX echo "\n" >> $MAININDEX fi z=`expr $z + 1` done

The latter also completes the end of the HTML and adds Last edit tag. We can then look at all our files and upload them to the server.

 # Connect to FTP and upload htmls.
ftp -n -v << EOT
user xxxx
prompt off
cd public_html/deyan-levski/test/
mput *.htm
cd post
mput post/*.htm

In an ideal world I can possibly extend this in the same fashion and make it a generic piece of code. If I do so, I will for sure write a proper post about it.

Date:Sun Mar 30 15:47:00 CEST 2014


Easing up the generation of these pages.

OK, I guess I am a bit old-fashioned, I am still keeping these pages in pure HTML and do not want to port them to blogspot, wordpress, etc... Except my stubbornness it might partly be that I find most of the blog templates quite "not-so-much-content-focused", instead these emphasize on shapes, colors and ads, rather than keeping information content as readable as possible (might not be the case with my HTML template though, but still...). One drawback of writing your pages in HTML is the difficulty to maintain a good content tracking and reduce the effort put into organizing these pages.

I am somewhat excited to be able to create and keep a good content management system which I hope will reduce my writing effort. In some hours of thinking, I have the skeleton of my system and decided to try it out, add a new (this) post, and see how it goes.

Date:Sun Mar 30 14:22:00 CEST 2014


Attacking a!b!=a!+b!+c! the brute-force engineering and analytic mathematical ways.

Not very long ago I had an argue about whether there is a solution to the equation a!b!=a!+b!+c!. It was an argue between a mathematician and engineer, so while my math friend was trying to find the solution to the problem the scientific (analytical mathematic) way I decided to give it a try and brute-force it using some nested loops in Matlab. Initially I somehow made a simple uncatchable syntax mistake and my program seemed to be looping forever. The very same evening my math soul continued with the analytical solution and finally came with a statement that the equation does not have a solution. We both agreed and assumed that we are all right.

Well, the day after we found out that there indeed is at least one solution. This is a=3, b=3, c=4. The conclusion I want to bring here is that no matter how good one is in his profession, his self-confidence should stay at maximum 0.999999999999999999.

Interested in the analytical solution? Read here. Interested in the brute-force method? Find the nested loop Matlab script here.

Date:Sun Mar 15 12:46:50 CEST 2014


Offset measurement of latched comparators.

During comparator design one is often (but not always) interested in the systematic and mismatch-related offset. When dealing with continuous-time open-loop comparators the offset measurement methodology is similar conventional OTA offset measurement e.g. DC sweep, while latched comparators require a somewhat more discrete-like manner of measuring offset.

One possible approach is to use a very precise (long sloped) linear ramp, and using massive oversampling and comparator decision storage. This approach seems to be a bit tedious as its precision is solely dependent on the ramp's slope.

A basic illustration of the linear ramp method.
A basic illustration of the linear ramp method.

An alternative method for measuring offset of latched comparators would be the binary search method. One can possibly use an ideal DAC to apply "search" voltages and depending on the comparator's decision reach a settling value with a constant binary-weighted precision. E.g. to achieve 16 bits of search accuracy only 16 cycles would be required. Here are some basic illustrative examples of the two methods.

An illustration of the binary search method.
An illustration of the binary search method.

The binary search method for measurement can be applied in various ways. One practical implementation was to implement the algorithm using Verilog-A and directly add a "search" instance where you can test your comparator directly in your existing SPICE simulation. Here is a very simple example of a possible implementation.

Code update guidelines after a reader's feedback. Thanks Stefi!

Hi, I changed some of your code because I found the array method quite confusing. What is the reason for using a large lookup table? This way, you are calculating all the values 2^16 values instead of just the 16 ones needed... I used something like: if (CompDecision > vTransComp) begin // Comparator output is high, inp>inn, ->make inp smaller iTop = iCompinp; iCompinp = iBot + (iTop-iBot)/2; end else begin // Comparator output is low, inp < inn, make inp larger iBot = iCompinp; iCompinp = iBot + (iTop-iBot)/2; end thus directly calculating the values if needed. The iteration stops after 16 cycles, which is the same as having a resolution of 16. So I just tried to keep it easy so I can understand it. Just my 2¢ regards, Stefi

Indeed there is no need to calculate all 2^N code steps and later on comare them in a look-up table fashion. This is some code inefficiency which has not been realized back in the day, my lord... Nevertheless, the code (either way) works and it is the concept that matters. For this reason I have left the old code untouched, as it has been tested. I am however encouraging you to explore and write your own implementaton. Nevertheless, here's the original version and an aka inefficient implementation:

// VerilogA for daisyCycAd, daisyCycAdBinSchSAR, veriloga
// A component handy in comparator offset measurement. Uses a binary search algorithm with a "dive" coefficient of 2. See comments for more information.
// Initial version P1A - Deyan Dimitrov

`include "constants.vams"
`include "disciplines.vams"

module daisyCycAdBinSchSAR(vCompIn, vCompOut, vClk, vdd, gnd, vCompRef);

input vCompIn, vClk;

output vCompOut, vCompRef;

inout vdd, gnd;

electrical vCompIn, vCompOut, vClk, vdd, gnd, vCompRef;

parameter real vTransClk = 1.65;
parameter real vTransComp = 1.65;
parameter real vSchTop = 3.3;
parameter real vSchBot = 0;
parameter real vCompReference = 1.5;
//parameter integer Resolution = 16;
parameter integer NrOfCodes = 65535;
//parameter real tCompSpeed = 100e-12;
real vRefInReal;
real vBinSch;
real vComp;
real scharray[0:NrOfCodes];
//real next;
integer imid;
integer imin;
integer imax;
integer i;
integer codes;

analog begin


       vBinSch = vSchBot + (vSchTop-vSchBot)/2;  // Mid point as a start of the search

       imin = 0;
       imax = NrOfCodes-2;
       imid = (NrOfCodes-2)/2;

       	   for (i = 0; i < NrOfCodes-1; i = i + 1) begin
       	     scharray[i] = (((vSchTop-vSchBot)/NrOfCodes)*i)+vSchBot;   // Creating reference array

	   $strobe("Array Max %g", scharray[imax]);
	   $strobe("Array Min %g", scharray[imin]);


       @(cross(V(vClk) - vTransClk, 1)) begin

//       next = $abstime + tCompSpeed;    // Possible internal compensation for comparator's delay
//       end
//       @(timer(next)) begin
//       $strobe("Imax: %d", imax);
//       $strobe("Imid: %d", imid);
//       $strobe("Imin: %d", imin);

       vComp = V(vCompIn);   // Strobe comparator decision
//       vRefInReal = V(vRefIn, gnd);

       if (imax >= imin) begin	// Continue searching if imax >= imin

       	  if (V(vCompIn) > vTransComp) begin      // Find-out which sub-array to search
//       	  vBinSch = vBinSch + (vSchTop-vBinSch)/2;
		  imin = imid + 1;	          // Change min index for the upper sub-array
		  imid = imin + ((imax-imin)/2);  // Update imid to be used for strobing-out
//       	  vBinSch = vBinSch - (vBinSch-vSchBot)/2;
		  imax = imid - 1;		  // Change max index for the upper sub-array
		  imid = imin + ((imax-imin)/2);  // Update imid to be used for strobing-out


       vBinSch = scharray[imid];		  // Look-up at the reference array and assign to vBinSch (Votage to be strobed-out)

       V(vCompOut) <+ vBinSch;			  // Update search voltage
       V(vCompRef) <+ vCompReference; 		  // Update comparator reference



The whole principle is simple and self-explanatory. Some delay between the latch clock and S/H clock of the search component is required to compensate for the comparator's speed. Here are some practical usage illustrations.

A primitive testbench proposal.
A primitive testbench proposal.
Component settings.
Component settings.
Offset search progress.
Offset search progress.

If you find this useful the component's symbol for Virtuoso 6 as well as the *.va code can be found here.

Date:Sun Mar 11 12:46:50 CEST 2014