2017 Laboratory 3: SPICE, DNL, INL, spectral analysis


Task:


Simulate a digital to analog converter. Extract VFS, INL and DNL and do a spectral analysis.

Start LTSPICE.
Save all schematics of an DAC to your local working drive.
Load the circuit 4Bit_C2C_DAC_Test into LTSPICE.
Make sure the ramp is active and simulation time is 16µs checking the VIN statement and the .tran statement.
Start the simulation for a ramp: Simulate -> Run
  1. Include the schematic in your report
  2. Include the output waveform in your report.
    Select the waveform window. Tools-> Copy bitmap to clipboard. Paste the bitmap into your report.
  3. Include the SPICE netlist in your report.
    View->SPICE netlist.
  4. Include the SPICE Error log in your report.
    View->SPICE Error log.

Discuss the operation and the results.

The '.save V(vout)' command line makes only V(vout) available for plotting.
This is needed for further data processing.
You can comment the line out using a '*' or a ';'.
  1. Use the tool ReadRawFile_ADC.html for reading one column of LTSPICE data.
    '.save V(vout)' has to be active.
    The output values will be scaled with the range into positiv integer values.
    Select a convenient output range for simulation (integer * #steps = integer * (2N-1)).
    The timestep will sample data in the LTSPICE raw output file at 1/2*tS, 3/2*tS, 5/2*tS ..
    Select a timestep matching the simulation.
    Select the option for ramp INL, DNL analysis.
    Select your LTSPICE raw output file.
  2. Report minimum and maximum value, INL and DNL and discuss the results.
  3. Change the simulation for a sinewave:
    Simulation time 256µs to get 256 values.
    Activate the input sine signal.
    Redo the simulation.
    What happens for different starting values 'Phi' of the voltage source?
    Use the tool ReadRawFile_ADC.html with the option 'Map to positive integer' for reading one column of LTSPICE data.
    Use the tool FFT_Javascript_2017_Calibration.html for doing a FFT and a histogramm test.
    Paste the integer data into the 'Input Data' field, do read 'Integer Data' and 'Generate Charts'.
    Document your results and discuss signal to noise behaviour.
  4. Redo INL, DNL and signal to noise ratio calculations with errors in capacitances:
    Report and discuss the results.


Report


Make a report as a pdf document from a Word document or a web page.
You can use the source code of this web page or there is a web page template available here.
Additional files are here as an zip file (39 MB).

Send a ziped group directory with your data containing also a printout of the webpage in a pdf file to joerg.vollrath@fh-kempten.de.

You can use the freeware program PDF Creator for generating the pdf file.

The directory should be named with the year, group number and last name

<year>_Group<###>_<Last_name>
Example: 2017_Group01_Vollrath

In this directory put the html and pdf file.
The file name should contain the date, the laboratory and your last names.

<year>_<month>_<Date>_InEl_Lab02_<Last_name1>_<Last_Name2>.pdf
Example: 2017_10_24_InEl_Lab03_Vollrath_studentx.html
Example: 2017_10_24_InEl_Lab03_Vollrath_studentx.pdf





Grading:

Each question should be answered. The answer should be correct/make sense. There should be some text discussing the work strategy, obstacles and results. The submission date will be graded. Submission should happen until 22.11.2017. Late submission will be downgraded. A nice document format and correct use of English language and spelling is graded.