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PCB Layout using ADSNovember 29, 2005

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PCB Layout using ADS

Dr. B. FrankDepartment of Electrical and Computer Engineering

Queen's University


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MotivationNeed circuit more reliable than breadboard?

Working at RF/microwave frequencies?

Printed circuit board (PCB) is a good solution


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PCBPCB done on a substrate such as FR-2 or FR-4, though at RF/microwave frequencies special low-loss substrates are used (often obtained free from Rogers Corporation)


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PCB Design Procedure Layout software is usually used to to draw the

metallic traces, which tells milling machine where to move excess metal

Via holes are drilled through the board as necessary to provide a path between the top and bottom of the board.

The board is populated with transistors, RLC, integrated circuits, etc.


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PCB Layout using ADSAgilent's Advanced Design System (ADS)

schematic capture

circuit simulation

electromagnetic simulation

layout

We will focus on using ADS for layout in this guide.


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Layout using Autogeneration1.Create schematic using Lumped Components

with artwork

2.Add connecting traces (e.g. microstrip lines)

3.Generate layout from schematic

4.Modify layout to suit Abbreviated procedure outlined next, but more

detail in document posted on web


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1. Open ADSUnder Start menu in Windows, ads in UNIX

File | Create New Project


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2. Add passivesUse Lumped-With Artwork palette


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3. Set size of passivesEach R,L,C item has properties of W, S, L that specify pad size use data sheet to determine

pads


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4. Add active componentsCome in standard package sizes: see Wikipedia Surface mount technology

Transistor: select BJT or MOSFET palette, place on schematic, right click, Component | Edit Artwork, and select package size

IC: select a component with the right number of pins (e.g. in Eqn-based Nonlinear palette), select artwork


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5. Join everything with microstrip


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6. Export to layoutLayout | Generate/Update Layout


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7. Modify layout elementsMay need to move/rotate microstrip lines to prevent them from overlapping

Can add new lines using Insert | Rectangle

See Chapter 9 of the Schematic Capture and Layout manual


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8. Export to Gerber fileFrom layout window select File | Export, then select Gerber

Provide Gerber file to ILC technician


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More information Schematic Capture and Layout ADS manual

Tutorial guide at http://bmf.ece.queensu.ca/

Documents

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