Robust Low Power VLSI R obust L ow P ower VLSI Designing Printed Circuit Boards – PADS Logic Yousef Shakhsheer Robust Low Power VLSI Group Revision 1.0

Robust Low Power VLSI Revision History DateReviserNotes 1.04/30/12Yousef Shakhsheer (yas5b) 2

Robust Low Power VLSI Overview This tutorial is intended to get people started with the PADS flow and basic PCB schematic capture. We use PADS Logic for schematics and PADS Layout for PCB layout for this tutorial. 3

Robust Low Power VLSI Schematics 4

Robust Low Power VLSI Outline  Schematics  Creating a library/components  Create a schematic  Exporting designs to netlists 5

Robust Low Power VLSI Schematics  The schematic is a top-level symbolic representation of the circuit you are designing  It affiliates parts (symbols in the schematic) with nets (connections in the schematic) 6

Robust Low Power VLSI Open a new schematic 7

Robust Low Power VLSI Libraries  Libraries hold sets of parts (symbols and PCB decal information)  Libraries are not affiliated with a particular schematic or design so that parts can be re- used and shared 8

Robust Low Power VLSI Creating a Library 9

Robust Low Power VLSI Creating a Library 10

Robust Low Power VLSI Creating a Library 11 Keep on pushing up until tutorial is on the top of the list

Robust Low Power VLSI Parts  Parts reside in libraries, they contain all the information required to place a component onto a PCB  Affiliate schematic symbols with a PCB footprint (see Layout tutorial for more) 12

Robust Low Power VLSI Create a part 13  Lets create a part  SMT: LT Single Resistor Gain Programmable, Precision Instrumentation Amplifier  m/product/LT1167

Robust Low Power VLSI Create a part 14

Robust Low Power VLSI Create a part 15 Add part information. See the pictures for details. Hit OK.

Robust Low Power VLSI Symbol  Symbols are what show up when we add a part to a schematic  We can either create this symbol by-hand (from a set of pins and lines) or use a wizard to auto- generate it for us 16

Robust Low Power VLSI Let’s draw a symbol 17

Robust Low Power VLSI Setting a Decal Name 18

Robust Low Power VLSI Lets draw the decal 19

Robust Low Power VLSI CAE Decal Wizard 20 A simple tool for quick creation of multi-pin symbols.

Robust Low Power VLSI Return to the part editor. 21

Robust Low Power VLSI Back to the schematic File→Exit Parts Editor 22 You will get two warnings. You can ignore them for the time being Warning: Duplicate pin name RG for pin number 8 on Gate A. Warning: Part has no PCB Decal assigned.

Robust Low Power VLSI Let’s add a part to our schematic! 23

Robust Low Power VLSI Add a LT1167 and a 1206 resistor 24

Robust Low Power VLSI Schematic Basics  F2 to create wires  Two types of connections  Physical wire connection  Off page connectors: click on the wire and then right click, “Add off page connectors”  Additional you can use the ground symbol by click on the first part of the wire and then right clicking and selecting “Ground” 25

Robust Low Power VLSI Lets put together an example schematic Part numbers:  U1- LTC1167  U2- LDO – Digikey P/N - LP3996SD-3333CT-ND  U3- MicroUSB – Digikey P/N - A31727CT-ND  P1- Power Jack – Digikey P/N - CP-037A-ND 26

Robust Low Power VLSI Example (this is not a functional circuit) 27

Robust Low Power VLSI Other schematic entry tips 28  Right click on the schematic for the selection menu  You can make it so you can only click on/select only certain objects  Always change the background color before exporting/printing any schematics from PADs layout

Robust Low Power VLSI Netlists  The netlist affiliates a group of symbolic pins with a what is referred to as a “net”  We sometimes label these nets for convenience (Vcc and GND are common names) but we do not have to name all the nets  When the netlist is exported all non-named nets have their names auto-generated so the layout tool can correctly affiliate all the pins 29

Robust Low Power VLSI Export an Netlist for Layout 30

Robust Low Power VLSI On Netlist Export Two files will open up. 1.Whatever you named your netlist.asc – The netlist for your schematic 2.tutorial.err – An error report file (make sure you always check this) At this stage: 1.You haven’t assigned PCB decals, so you should see errors for this 2.You may also see single ended nodes 31

Robust Low Power VLSI Bill of Materials  Once we have created a PCB we will need to order all the components necessary to populate the board  The Bill of Materials (BoM) makes this easy and outputs a simple list of items in the schematic  Any field included in the attributes of a part included in a schematic is allowed to be added to the BoM for that schematic, this means we can have columns like DigiKey Part Number, Approximate Cost, or even product page URL if these attributes are added to the parts on creation 32

Robust Low Power VLSI Creating a Bill of Materials  File -> Reports 33

Robust Low Power VLSI BoM Export  The BoM is a text-based report but a CSV output file can be created (this allows an effected export to Excel)  The BoM is a useful tool both for ordering parts and also for population as it affiliates part numbers with part reference numbers in the schematic and layout 34

Robust Low Power VLSI See the Layout tutorial for creation of an affiliated PCB design You’re Done! 35