VLSI Data Conversion Circuits, Aug-Dec 2006: Syllabus/Assignments

Assignments
Assignment submission
Simulation resources
Syllabus and schedule

Assignments

1. Quantization, DAC characteristics: HW1; dac1.dat,dac2.dat
2. A/D converter test: HW2; a2dcodes.dat
3. ΔΣ modulators: HW3
4. DAC design: HW4; Dout.dat,Idac.dat
5. Flash A/D converter components: HW5
6. Pipelined A/D converters: HW6

Assignment submission

Submit all solutions by email as a single pdf file.

• You can use a wordprocessor of your choice and convert the result to a pdf file.
• If you have multiple files, you can use pdftk to combine them. This is installed under /usr/local in VLSI and TI labs. Documentation can be found at /usr/local/doc/pdftk/pdftk.1.html
• Another way to generate a pdf is to concatenate ps(postscript) files containing all figures and text(use enscript to convert text to ps) to a single ps file. Run ps2pdf on this file to get a pdf file.
  enscript -p p1.txt.ps p1.txt
  enscript -p p2.txt.ps p2.txt
  cat p1.txt.ps fig1.ps p2.txt.ps fig2.ps > out.ps
  ps2pdf out.ps eexxxxxx_hw01.pdf
  
• Name your file with your id as eexxxxxx_hw01.pdf so that it is easier for me to keep track of.
• Put your name and roll number on the first page. For joint submissions, put all the names on the first page and submit a single email.
• Regardless of the order in which you do the problems, rearrange the solutions in the right order in the submission.
• N people submitting jointly will all receive equal credit equal to 2^-(N-1)/2 times the graded credit for the assignment.
• Joint work masquerading as individual submissions(a.k.a. copying) will result in a zero on the assignments.

Simulation resources

Tools

• Matlab, Scilab, or Octave can be used for system simulations.
• Xcircuit is an open source tool for circuit netlisting. It is also an excellent tool for drawing publication quality circuits. Download the latest version of Xcircuit here. You might want to go through the schematic capture tutorial in order get familiar with the netlisting process. If you use machines in FPGA/VLSI/IE labs, check to see if Xcircuit is already installed.
• Eldo is a circuit simulator from Mentor Graphics. The Institute has purchased 50 floating licenses of this simulator for class use. The binaries are installed in the DCF as well as the FPGA and IE labs. Feel free to copy them to your hostel Linux PCs. Eldo works like any other SPICE, so if you are familiar with SPICE netlisting, it should be smooth sailing. To simulate a circuit, create it in Xcircuit and generate a netlist. Add the required analysis commands and include the MOS model files to get going. An extensive Eldo user guide (eldo_ur.pdf) should help point out the powerful features of the simulator. This guide (and others) can be found in the $anacad/documentation directory. To setup Eldo, see below.
• Xelga This is a waveform viewer from Mentor Graphics that understands Eldo output. Use this to plot your simulation outputs. A users guide (and others) can be found in the $anacad/documentation directory.
  
• Those who have access to Cadence for other projects can use it for all simulations.
  
• MOS models(0.18µm CMOS, 1.8V supply unless otherwise mentioned):
  • 0.18µm model file
  • 0.18µm process information.
  • Add the following line to your netlist to use these models with Eldo
    .option compat

Setup

1. Log on to the department ftp/ssh server 10.7.0.1 (athreya). Copy the directory /pub/mentor to some convenient location (/tools directory, if you have so) in your machine.
2. Add the following line to your /etc/hosts file
   10.65.0.45 moon.cc.iitm.ernet.in moon
3. Add the following lines to your startup script in your home directory
   
   For csh or tcsh: ~/.cshrc
   # ANACAD BEGIN #########################
   # ANACAD SOFTWARE Initialization
   setenv anacad /tools/mentor # (change as necessary. It is /pub/mentor in DCF)
   source $anacad/com/init_anacad
   # ANACAD END #########################
   setenv LM_LICENSE_FILE 1717@10.65.0.45
   set path = ($anacad/bin $path)
   
   For zsh/bash: ~/.profile or ~/.bashrc
   # ANACAD BEGIN #########################
   # ANACAD SOFTWARE Initialization
   export anacad=/tools/mentor # (change as necessary. It is /pub/mentor in DCF)
   source $anacad/com/init_anacad.ksh
   # ANACAD END #########################
   export LM_LICENSE_FILE=1717@10.65.0.45
   export PATH=$anacad/bin:$PATH
   
   

   For those who want to use the tool in DCF/FPGA Lab/IE Lab, follow the same procedure except steps 1&2.

Troubleshooting

1. If Eldo does not fire up : First make sure that the environment variables are properly set.
2. If Eldo complains about licenses : check if your machine is able to reach the license server (moon.cc.iitm.ernet.in or 10.65.0.45). If moon is not reachable, contact your network administrator.
3. If moon is reachable, but you are unable to run Eldo, run "lmstat -c 1717@moon" from your command line. If the result is that the license server is running, it means that your environment variables are not properly set. If the license server is dead, please contact Mr.S.K.Ramesh at the Computer Center (Phone 4980).
4. If Eldo crashes complaining about the kernel version, add the following line to .cshrc(and source it)
   setenv LD_ASSUME_KERNEL 2.4.1

Syllabus(Schedule)

• Applications of data conversion systems
• Continuous and Discrete time signals and systems
• External characteristics and nonidealities of Digital to Analog(D/A) and Analog to Digital(A/D) converters.
• Oversampled D/A and A/D converters
• Overview of D/A and A/D converter architectures
• Nyquist rate Digital to Analog converters
  • Current Steering
• Nyquist rate Analog to Digital converters
  • Flash converters: Single step, two step; Interpolation;
  • Multi step Flash converters, Pipelining