Video lectures from the iCS group @ IIT Madras

Testing equipment

The testing lab contains a number of high performance and expensive equipment. Acquaint yourselves with the equipment by reading the manuals to get the best out of them. Here is a list of instruments in the testing lab.

Purpose Document
Brief tutorial on data capture using 1682AD logic analyzer1682ad_data_capture.pdf
Histogram based INL/DNL measurements (Appln note from Maxim)inl_dnl.pdfinl_dnl.m
Tutorial for ORCADorcad_tutorial.pdf
LabView tutoriallabview_tutorial.ppt

OrCAD Tips

Drawing Schematics

  • Use seperate symbols for electrolytic capacitors and surface mount capacitors.
  • While using electrolytic capacitors, pay attention to the positive and negative terminals. Terminal 1 in schematic should be connected to higher voltage and terminal 2 to lower voltage.
  • Maximum value of non-polar surface mount cap is 1uF (@ modi electronics, ritchie street).
  • Use seperate symbols for thru-hole resistors and surface mount resistors.
  • There is a pushbutton in Orcad to generate 'Bill Of Materials'. This will aid in determining which all components to purchase.

Printing Schematics

  • To save schematics as PDF, first you will need to install PDF995 ( a free software).
  • Change print setting to 'Landscape', and output as 'PDF995'.

Placement

  • First switch off 'Online DRC'. Else you will be unable to reorder the footprints.

Routing

  • Before starting to route, we must fix the width of each net. Tools–>Net–>Select from Spreadsheet. Here we can fix the min,typ and max width of each net. For GNDA and VDDA it is 12,50,100, and for other nets 12,25,50.
  • To start routing click 'Add/Edit Route Mode' button in the task bar.

Submission

  • .MAX file contains the layout and .DSN file contains the schematic.
  • Only the .MAX file needs to be submitted for fabrication. No need to generate the GERBER files.
  • The shape of the PCB need not necessarily be a square/rectangle.

PCB Fabrication / Component purchase

Fabrication

  • Printed Circuit Services(Zeta), I-1, Dr.V.S.I Estate, Near NIFT, Thiruvanmiyur. Ph: 22541641, 42150860, Email: plot@zetapcs.com
  • Tessolve

Technical information about the PCB

  • Type of material used : FR-4(an abbreviation for Flame Retardant 4, a glass reinforced epoxy laminate used for making printed circuit boards.)
  • Dielectric Constant: Varies according to the frequency applied and depends on the vendor.(A value of 4-4.5 seems to be appropriate for high frequency designs >1GHz)
  • Standard thickness of board: 1.6 mm
  • Thickness of copper trace: 35 µm

The above information can be used to determine the trace impedance.

Component Purchase

  • Modi Electronics, No 6, 1st floor, Ritchie Street. Ph: 28414140
  • Mercy Electronics, L.B Road, Adyar. Ph: 24464481
  • Mency Electronics, Tharamani Road, Velachery. Ph: 22434773, 42082097
  • Texonic, Ritchie Street. Ph: 28410638
  • Globe Tronics, Ritchie Street. (All kinds of male/female connectors, adapters etc.) Ph. No: 42119262, 42149503
  • SRICOM(Srinar Communications) (RF Cables, Connectors, and other accessories…) http://www.sricomworld.in/; email : mtk@sricomworld.com
    Ph.No : +91 9841005125 (Mr. Ismail)

Assembly

Sri International