Outcome 1

Investigate ECAD Systems

Expectation after studying this outcome? Student able to source the market for ECAD

tools based on their work requirement.

Student able to identify whether the features of a particular ECAD system fulfill their needs.

Student able to make critical comparison among the ECAD tools in the market.

What is an ECAD?

ECAD - Electronic Computer-Aided Design. The use of computer technology to aid in the

drafting/design of a product.

Type of ECAD tools according to industries Board-level design

PCB layout design tools SPICE simulation Analogue and Digital schematic design tools

IC-level design ASIC layout design tools SPICE simulation PLD schematic for HDL simulation

Categories of ECAD tools (pg 1-2) According to stages of the design process:

Design entry stage

Functional verification stage

Physical design stage

Physical verification and testing stage

Design entry stage Designer use pre-defined schematic symbols to

design desire circuit. The circuit is then translate into SPICE script for

simulation. Without this tools, designers wishing to simulate

their circuits will have to write the SPICE scripts themselves.

Functional verification stage Tools used at this stage are simulation and

analysis tools. Think of them as your virtual lab instrument. Designer will know from simulation results

whether a design idea is workable or not. Three major types of analysis (Appendix C):

AC analysis Analyze circuit gain and phase across a range of frequency.

DC analysis Analyze DC voltage level at various circuit nodes.

Transient analysis Time domain analysis simulates circuit response over time.

Physical design stage Conversion from schematic design into layout

design. The layout maybe PCB layout or IC-mask layout. Nowadays, these tools will do an automatic

conversion.

Physical verification and testing stage Physical verification tools ensures that the

physical layouts conform to design rules so that the intended functionality is not jeopardized by layout-induces parasitic, cross-talk and other effects.

The verification tools include: DRC

Design Rule Check ERC

Electric design Rule Check LVS

Mask Layer Versus Schematic check

Importance of ECAD tools (pg 1-4)

Without computer simulation, the workability of a design could only be tested out after board assembly process.

Here to known whether the circuit workable or not!

Waste of time and resources $$$$$.

Importance of ECAD tools Without the ability to do testing and verification at each

stage, you will find it very difficult to single-out defects after assembly process.

Because there are more variables to rule out. Is the design itself flawed? Is the PCB layout erroneous? Is some parts or components wrongly assembled?

You would have a tough time to rule out the real root cause of the problem.

And, in manufacturing industry, time and $$$$$ is the real problem so, this can’t be allowed to happens.

Design process improved with ECAD tools

Having implement ECAD system in the process, any design flawed can be detect through simulation.

ECAD system here

Another ECAD system here

Design process improved with ECAD tools With ECAD virtual simulation capability, any

design flaw can be detect and re-design without involving actual assembly and testing on real physical parts.

This would certainly prevent wastage of time and resources at the PCB layout and assembly stages.

Common features of ECAD systems Below list some common features that a

designer would find desirable as the basic package of the ECAD systems they seek to purchase and use (pg 1-7 to 1-19):

Schematic capture SPICE model simulation HDL model simulation Components database / library Hierarchical design Mask layout editor Cross-section viewer Verification tools Waveform viewer PCB layout editor

Schematic capture (pg 1-7)

Schematic capture allows user to choose from a list of pre-generated SPICE-model schematic component and drop them onto the design workspace.

Drag and drop featuresSPICE-model

SPICE-model

SPICE-model simulation (pg 1-9) SPICE-model simulation using DC analysis, AC

analysis and transient analysis. And some virtual instrument such as multimeter, oscilloscope, logic analyzer…etc.

HDL-model simulation (pg 1-12) Take a symbol, and describe its function using

Hardware Descriptive Language. Thus, allowing the symbol to be used directly in

ECAD systems that recognize HDL language.

HDL Symbol

Component database/library (pg 1-13)

It would help the designer a great deal if the components database/library covers extensively those real components available on the market.

Hierarchical design (pg 1-14)Basic cell

Flip-flop

Shift register

Mask layout editor (pg 1-16)

Allows designer to graphically design the layout masks, automatically tracking the layers, and providing basic primitives for the designer to build circuits with.

Cross-Section ViewerMask layout of entire chip

Cross-section viewer (pg 1-17)

A feature often comes with mask layout editing tools to help user verify on-the-go the cross sections of doped regions.

Very helpful tool for designer as the doping geometries never ideal and important to make sure masks designed will not result in under-doped regions or over-doped regions.

Inverter Cross-section

Verification tools (DRC, ERC, LVS) (pg 1-17)

Most ECAD software often includes verification algorithms that help the designer verify the layout design.

Design Rule Check is a feature available in most IC layout design editor.

Electrical Rule Check is a feature available in most board-level design editor.

Layer Versus Schematic check is between schematic and mask layout checking.

Verification tools (DRC, ERC, LVS) (pg 1-17)ERC in Board-level editor

DRC in IC-mask layout editor

Waveform viewer (pg 1-18)

When designing IC layout, timing of the circuit is a very crucial consideration.

For example, a longer metal routing means slightly longer delay.

So, you should check to make sure that those additional delays do not result in the circuit not performing according to the required function or affects the noise immunity of the design.

PCB layout editor (pg 1-18)

Two ways to use PCB layout editor. One is to design the circuit using component

available from the editors’ library. The other is to convert the designed circuit into

PCB mask layout to a level not possible with manual drawing.

Such precision had been crucial in design of surface-mount PCB.

ECAD tools on the market (pg 1-20) Range of available ECAD tools on the market is

too wide and extensive to be made into a comprehensive list.

Below list some of the EDA tools according to categories.

ECAD tools on the market (pg 1-20)

Critical review of ECAD Systems There are few critical areas of considerations

when choosing ECAD systems (pg 1-22): System requirement Ease of use Extensiveness of component library Range of simulation and verification tools provided Efficiency of simulation algorithm Possibility of importing from or exporting to other ECAD

software.

System requirement (pg 1-22) Software

So far, the best ECAD software on the market are made of UNIX operating system.

It may not necessarily mean you have to change OS in order to use an ECAD system.

Would it benefit in the long run to invest in the state-of-the art ECAD system, even if it meant changing the OS of your workplace?

Hardware Hardware requirement tend to be very demanding.

System requirement (pg 1-22)

You should make sure your hardware could support all the nice features available from ECAD software of your choice.

Also, you must decide whether your job requires high-end features or not.

Ease of Use (pg 1-23)

Some ECAD solution providers would have you believe that features such as “schematic capture” or “drag-&-drop” equate “ease of use”.

But that is not necessarily the case. Take an example:

For Multisim software, it is easy to search and use analogue components.

But for digital devices, this will be a big headache for the designer as the Multisim categorized all the IC according to family like LS family and LC family without much info.

Unless the designer knows all the part numbers of all the IC, or has a data book right next to him, else he will find it difficult to even just search for a 4-bit binary counter.

Extensiveness of component library (pg 1-24) Any design you make eventually have to be built with

real parts. So, it is generally advisable that you design around what

available parts you have to avoid the high cost custom-made components.

And this would be so much easier to do if your component library reflects the most up-to-date market component range.

Most ECAD packages nowadays allow users to download net-lists of newly released components from the internet to update their component library. This is a very desirable feature.

Range of simulation tools provided, or range of verification tools provided (pg 1-25) The rule is simple: the more the merrier. But of course, in some cases, more features

could spell higher cost. So, if you really do not need certain features,

you do not really have to buy the more expensive ones with more features.

It boils down again to your actual needs.

Efficiency of simulation algorithm (pg 1-25)

The availability of simulation tools does not necessarily mean they perform well or easy to use.

If possible, you should try out demonstration versions of software before buying it to find out if the simulation tools work as claimed.

Possibility of importing from or exporting to other ECAD software (pg 1.25) It is good that the ECAD software you procure allows

importing from or exporting to the file formats of other popular ECAD software.

For example, the client of your company may not use the same ECAD software as you are using.

And it would then be very difficult for them to view your samples if your ECAD software cannot exporting to your customer file format.

Also, the ability of importing is desirable in cases where you have the opportunity to download existing net-list from other file formats to incorporate into your own design.

Assignment 1

10% of the total coursework marks. Maximum 2 persons in a group. Provide the web address of information

gathered. Marks will be deduct if the lecturer finds out any

“KES TIRU-MENIRU”. In some case, zero marks for the particular group of student.

Cut-and-paste directly from the source, marks will be deduct.