Cadence Custom IC Design Blogs

Things You Didn't Know About Virtuoso: The View From Above

stacyw — Thu, 09 Jul 2009 13:00:00 GMT

A few years ago I bought a wonderful book called "Earth From Above". An amazing French photographer has put together a collection of truly unique aerial photographs of all kinds of unusual natural and man-made landscapes. It's fascinating how different things look from high altitude--sometimes you can hardly recognize what you're looking at. You wonder what that same scene would look like if you were down at ground level. Well, maybe that's not the case when you're looking at penguin poop from space, but you know what I mean.

Okay, you guessed it, as usual, now I'm going to tie this subject into Virtuoso. You see, one of the new assistants available in IC6.1 is the World View Assistant. This handy little widget is activated by--you guessed it--clicking your RMB at the top of your schematic or layout window and selecting "World View". The assistant pops up in the corner of your window with what the manual refers to as a "panoramic view" of your complete schematic or layout.

The yellow rectangle, or "view box", superimposed on the view represents the current design area displayed in the main canvas. You can resize this rectangle using the drag handles on its edges. This will change the zoom level in the main canvas to display the area under the view box. You can drag the view box around to different areas of the design and the main canvas will pan right to that area. Or just click in the World View at the location you want to see and the main canvas go there. And since layouts tend to have just a bit more detail than schematics, the World View Assistant in layout has a menu available on the middle mouse button which allows you to zoom in and out of the World View itself to more easily guide the viewing area.

It's that simple. No zooming in and hitting the arrow keys a zillion times to pan across to where you were going. No "bindkey f", then zoom in over and over again. Just move the little yellow rectangle around and you'll know just where you are.

Bonus Tip: I know we did a whole article on RMB a while back, but did you know that there are some cool things tied to the MMB (middle mouse button) as well? The one I found particularly useful has to do with toggling the direction of pins while you're placing them. Like many people, when I'm drawing schematics, I often find myself placing a whole pile of pins all at once. Some are input, some are output, some are in/out. It's kind of annoying to have to keep popping back to the form to change the direction.

What I didn't know was that clicking Shift-MMB while in the "Create Pin" function will toggle through the possible pin types. Also, just clicking MMB allows you to rotate the pin before placing it (MMB will also do rotation during the "Create Instance" function--very handy!).

I did run into some trouble with this when I was using VNC and I had previously reprogrammed my middle mouse button in Windows, but these functions can be easily bound to a different key or mouse button.

That's all for now. Keep watching this space for more handy features in Virtuoso IC 6.1.

Stacy Whiteman

Things You Didn't Know About Virtuoso: Which Way Should I "Go"?

stacyw — Tue, 30 Jun 2009 17:00:00 GMT

Just a short post this week, as I've been quite busy recording videos for some of our Virtuoso Platform Webinar Series, the last of which, covering Spec-Driven Design, airs Tues. June 30.

Recordings of this and past webinars can be found here. (If not posted there yet, they will be available soon). They've called these the 300-series webinars, a college course numbering analogy to let you know that you'll be getting a bit more technical depth and fewer colorful marketing slides...

You may have found, in experimenting with some of the new Virtuoso assistants (like the Navigator or the Property Editor Assistant) or toolbars (like the Bookmarks or Workspaces toolbars) that you've seen a menu entry for something called "Go". Hmmm..."Go" where? I'd like to go to the Bahamas, how about you? Well, unfortunately, this is not that kind of "Go" (it's also not an ancient Chinese board game that I really suck at).

Take a look up in the upper left corner of your web browser. See those arrows? Yep, it's that kind of "Go".

To display the Go toolbar, click RMB in the area just above the schematic canvas and select "Go". By default, it appears as a 2nd row toolbar, but you can move it around just like any other toolbar--by clicking the left mouse button on the triple-vertical-bar drag handle at one end of the toolbar and dragging it to any edge of the window.

It might not do much at first, in fact all the icons will be grayed-out until you start navigating around your design. Once you open a different cellview or descend into a sub-block, the arrows on the Go toolbar work just like the arrows at the top of your web browser. You can use the left and right arrows to move back and forward through the cellviews you have displayed. The red arrow to the right of the back and forward buttons allow you to jump forward or back to any of these cellviews right away. Again, just like your web browser.

But wait, you say, my web browser doesn't have any up arrows. What's up with that? (No pun intended--well, maybe a little..). As you've probably guessed, since Virtuoso operates on data which is intrinsically hierarchical, we've added the up arrows to intuitively take you back up your design hierarchy after you've descended. The up arrow with the little bar over it takes you immediately to the top of the design.

Well, that's all for now. Next up--another way to view the world...and extra bonus tips.

Stacy Whiteman

Optimization Environment Enables Effective Reuse of Existing Design Modules

Hiro Ishikawa — Fri, 26 Jun 2009 13:00:00 GMT

In order to complete a brand new design on time, it is an important factor to effectively reuse existing design modules. The use of an automatic optimization quickly and easily increases design reuse efficiency. The following figures are examples of a source layout and an optimized result made by Virtuoso Layout Migrate. Virtuoso Layout Migrate optimizes a design automatically by satisfying design specific constraints. The shape of the source layout can be maintained in the optimization result perfectly.

Before Migrate

After Migrate

One important issue that we need to carefully consider is how easily the result can be obtained. Even though the high quality optimization is possible, it would be useless if a lot of work is required to get it.

Cadence’s Virtuoso_XL, and GXL automatically extracts design constraints including Symmetry placement required for a design optimization from connectivity information in a schematic view and delivers them to a layout view via Constraint Manager. The design constraints delivered to the layout view will be applied as well as constraints added by a user manually during the optimization.

This optimization flow is as follows.

The following Fig 1-a shows the contrarians extracted by Circuit prospector. Fig 1-b is a migration result with respecting the design constraints extracted by Circuit prospector, and added by the constraint manager.

Fig 1-a. Automatic design specific constraints extraction by Circuit Prospector

Fig 1-b. Automatic design constraints addition via Constraint Manager (Schematic -> Layout)

Cadence Virtuoso XL, GXL can easily and automatically achieve extracting, maintaining, and applying complex design specific constraints that was "impossible" a decade ago. Cadence is only company offers robust, and comprehensive integrated design re-use flow in Virtuoso XL, GXL.

Hiroshi Ishikawa

Things You Didn't Know About Virtuoso: RMB, OMG! ;-)

stacyw — Tue, 23 Jun 2009 13:00:00 GMT

I apologize for the Internet slang in the title (urbandictionary calls OMG "the most irritating piece of chatroom vernacular in existence"), but I couldn't resist. Ever since IC6.1 came out, it seems like every other question gets answered using the three-letter acronym (that's TLA for those in the know), RMB. RMB to open an assistant, RMB to do this, RMB to do that. If you can't find it anywhere else, look under your RMB (oh sorry, it means Right Mouse Button).

Well, the other day as I was doing just that, I saw some commands on the RMB that I had never realized were there. I started looking around and realized that, hey, they've added a bunch of stuff on the right mouse button that's pretty handy.

So here's a quick list of a few things you might want to try with your RMB. I realize that most of these functions already have bindkeys, but heck, sometimes I don't want to have to put down that sandwich I'm holding in my left hand in order to press the "e" key...

In a schematic with nothing selected
- View Fit
- Add Instance
- Add Pin
- Add Wire
- Return (if you have descended in the hierarchy)
In a schematic with a wire selected
- Delete
- Add Wire Name
- Add Probe
In a schematic with an instance selected
- Copy
- Delete
- Rotate
- Descend Read
- Descend Edit (cool, no more Shift-E--actually, did you know that now if you double-click on an instance, it does a Descend Edit too?)
Similar functionality is available in layout as well
All the new IC 6.1 assistants (Navigator, Property Editor, etc.) have context-sensitive RMB menus to do the most commonly-used command

Bonus Tip: If you have a mouse with a wheel, scrolling the wheel up and down will pan the schematic (or layout) up and down, holding Shift and "wheeling" will pan left and right and holding Ctrl and "wheeling" will zoom in and out. For those of you so inclined, the bindkey designations for wheel scrolling are Btn4Down and Btn5Down and can be programmed just like any other bindkeys.

Well, now you can do a huge heap of your daily editing tasks using only one hand. How great is that? Stay tuned to this space for more Virtuoso tips and as always, feel free to share any tricks of your own or comment on what you like, don't like or would like to see in Virtuoso.

Stacey Whiteman

Things You Didn't Know About Virtuoso: Managing Your Real Estate - Part 2

stacyw — Tue, 16 Jun 2009 13:00:00 GMT

I keep my toothpaste in my bathroom. I keep the paprika in the kitchen. I keep the band-aids in the bathroom near the living room. Two points here. First, I keep the tools I need near the place where I do the activity for which I might need them. Second, I try to always keep things in the same place so I know where they are when I need them. Sounds sensible, right? Dinner would never be ready on time if I had to keep walking over to the bathroom to get spices. And I certainly don't want to run around the house bleeding while I try to find the band-aids.

These are the same principles behind Workspaces in IC61. Now, if you're bleeding profusely, you'll still have to get up and go find a band-aid (or call 911), but for most of your daily work activities, using Workspaces in Virtuoso enables you to have the tools you need arranged where you like them for the tasks you're doing at any given time.

We've talked in this space about some of the new assistants available in IC61 (Navigator, Property Editor...others we haven't discussed yet). I'm sure you've also noticed the new toolbars at the top of the screen. All these elements can be enabled, disabled, resized and moved around to your heart's content. When you're working with a huge schematic, you might want the Navigator and the World View Assistant so you don't have to keep zooming in and out. When you're first drawing a schematic you might want the Property Editor Assistant on the left and the Create and Edit toolbars on the right for quick command entry.

To get started, turn on the Workspaces toolbar (Window->Toolbars->Workspaces). It usually shows up in the upper right corner of the window. Workspaces apply to a specific application type (schematics, layout, ADE XL) and Virtuoso comes with several predefined workspaces for each application. For example, the schematic editor has Basic, Classic, and Explore, among others. Just pull down on the cyclic to try out some of the different arrangements available out of the box.

This is where the fun begins. Rearrange some assistants and toolbars. You can even undock the assistants and have them floating outside the main window. Now click on the icon just to the right of the cyclic to save your own custom workspace. You can create as many different workspaces as you like in order to have the right tools for each task right where you want them.

So next time your boss comes in frantically talking about how the project is bleeding $$$, you'll know right where you put the band-aids.

More information on Workspaces, including how your CAD department can create custom workspaces to be shared with everyone in the project, refer to the Virtuoso Design Environment User Guide.

Thanks for trying out some of these great new features. Please leave your comments and let us know about your experiences (good or not-so-good).

Next time we'll talk about some commonly used functions that I'll bet you didn't know were hiding right under your fingertips...

Stacey Whiteman

Things You Didn't Know About Virtuoso: Managing Your Real Estate - Part 1

stacyw — Tue, 09 Jun 2009 13:00:00 GMT

Yeah, right...in this economy, don't talk to me about real estate. But I'm not talking about home prices, I'm talking about that territory on the screen right in front of you where you spend your day drawing and clicking and arranging and rearranging in order to accomplish your job. Cadence has given you lots of tools to help you develop your little plot of land. Just recently in this blog, I've told you about 2 new ones, the Navigator Assistant and the Property Editor Assistant. They can be very useful, but maybe you're starting to feel that having all of these tools lying around is making things a bit cluttered. How am I supposed to build my house with this bulldozer in the way?

Well, that's what I'm here for. I've got a few great tips for organizing those assistants so you're not tripping over them any more.

Let's start with the basics. Turning an assistant on or off can be done from the Window->Assistants banner menu, or using the right mouse button (RMB) menu somewhere in the area at the top of the window. Once an assistant appears, what can you do with it (besides the task it was designed for, of course)?

You can click and drag the edges to resize it (look for the cursor to turn into a pair of parallel lines--this is your drag handle)
You can click on the X in the upper right corner of the assistant to close it (I'll be you figured that out already, didn't you?)
You can click on the middle of the 3 icons in the upper right corner of the assistant (or simply double-click anywhere on the top bar of the assistant) to undock it.

Egads, now what? It's floating free with a life of it's own. Well, not really. It's still integrally tied to the main window it came from. You can still cross-select with the main canvas and the other assistants. But now you can grab it by the little red title bar at the top and drag it off to the edge of the screen (or even onto your 2nd monitor if you're lucky enough to have a double-wide) where it will hover obediently, doing its job. You can resize it just as you would any regular window, by grabbing and dragging its edges or corners so you can see all its contents without scroll bars.

If you double-click on the title bar of the assistant (or click the middle icon again), it will dock itself right back where it came from.

Now you may have noticed while you were dragging your little friend around that over some areas of the main window, a big gray blank area would suddenly appear near where you were moving the assistant. This is to show you the different areas in the main window where the assistant will dock if you drop it there. You can dock assistants around any of the edges of the central canvas.

Bonus Tip: If you want an assistant to remain free-floating, hold down the Ctrl key while you drag it.

Extra Bonus Tip: Did you know that assistants can be tabbed on top of each other? Simply undock an assistant, drag it by it's title bar and drop it when your mouse cursor is somewhere inside the body of another assistant. Voila! The 2 assistants (or 3 or 4 or...) are now overlapping with handy little tabs at the bottom so you can switch between them.

And now for my last trick for today, I'm going to make them all disappear! Do you have an F11 key on your keyboard? Press it. Uh-oh, where'd they all go? Press it again. Whew, that was a close one. The F11 key will hide and show all the assistants you have activated at any given time so you can clear your working area with a single keystroke.

For those of you whose function keys don't go to 11, you can do the same thing by selecting Window->Workspaces->Show/Hide Assistants or clicking the far right icon in the Workspace toolbar. What are Workspaces, you ask? Tune in next time to find out...

As always, please feel free to comment or share your own tips and tricks...

Stacy Whiteman

Things You Didn't Know About Virtuoso: Editing Properties

stacyw — Mon, 01 Jun 2009 13:00:00 GMT

When I was growing up, my mother would usually bake a ham for Christmas dinner. She would always cut a slice off the side before putting it in the pan to cook. One day I asked her why she did this and she replied that her mother always did it that way. Now, I've never been the type of person who easily goes along with the "because we've always done it that way" kind of answer, so I asked my grandmother the same question. Turns out she had to trim the side of the ham because she didn't have a pan big enough to fit it in!

Okay, hold that thought. Now, quick, how do you edit the properties of a schematic instance? All together now, "q", right? Of course, everybody knows that. You select the object(s) you're interested in (making sure you don't accidentally select any extra pins or wires you didn't want), then you press "q". Then you reach up and move the property editor form out of the way because it's ginormous and blocks your schematic. You make a change to the first instance, then reach down and click "Next". Repeat this until your task is complete and click "OK" to get rid of the form. Maybe if you're really daring and you want to make the same edit to several instances at once, you reach up and use the somewhat intimidating "Apply to all selected instances of same master" cyclic fields at the top of the form and hope that you didn't inadvertently change something you didn't mean to.

This isn't a bad way to do things, but what if there was a better way? What if you didn't have to wear out the "q" key on your keyboard quite so fast? What if you could see the properties for more than one object--at the same time (gasp)? What if somebody gave you a bigger pan so you wouldn't have to throw away that extra slice of ham?

Get to the Point Already...

Next time you reach for that "q" key, try this instead... Go to the menu and select Window->Assistants->Property Editor. You'll now see the new Property Editor Assistant docked next to your schematic. It works much like the old "q" form with some very useful twists.

If you select multiple instances, you can see the property values for all of them at the same time. Just click on the little plus sign ("+") next to the property name to see the values for each instance.

If your selected set contains objects of different types (e.g. you accidentally selected some wires and pins along with the transistors you wanted), you can filter which type is displayed using the object category pulldown at the top of the assistant.

Objects are cross-selected in all relevant assistants (Navigator, Search Assistant, Circuit Prospector, Constraint Manager, etc.) as well as in the schematic canvas for easy identification and manipulation in the associated applications.

You'll probably notice some color-coding in the form. Grayed out lines are non-editable. Blue italics means the property is set to its default value. Bold orange text indicates that the selected objects do not all have the same value for that property.

To make a change, just click in the desired value field and start typing. If you want to make a change to just one instance, type on the line next to that instance's name. If you want to change a property for all the selected instances at once, type on the line next to the property name. It's that simple.

So you see, you don't have to do something a certain way just because that's the way you've always done it. I know your little finger will still have the reflexive impulse to reach for the "q" key (I still do it too sometimes). But the next time you've got some serious property editing to do, try calling upon the new Property Editor Assistant to make your work a little easier.

More information can be found in the Virtuoso Schematic Editor XL User Guide. There is also a video demonstration of the Property Editor Assistant in the Virtuoso Custom IC Video Library on Sourcelink.

Coming Attractions

Now that you've started using some of the new Assistants in IC61, I can hear some of you wondering where you're going to be able to find room for them on your screen. Not to worry, I've got lots of handy tricks to show you next time to give you plenty of elbow room on your monitor...

Stacy Whiteman

Things You Didn't Know About Virtuoso: Navigator Assistant

stacyw — Tue, 26 May 2009 13:00:00 GMT

Have you ever found yourself working with a massive schematic having to constantly zoom and pan around to find the block you're looking for (since they all look alike from high altitude)? Then you descend into the block only to find that the sub-block you really wanted is somewhere else? Well, pop back up and start over again...

Have you ever run a simulation which finds a problem with transistor I44.I23.I0.I25.NM2? Again, you zoom and pan around looking for instance I44, then descend into it and do some more zooming and panning to find I23. Lather, rinse, repeat until you finally arrive at our destination. Maybe you have a dim recollection that there is a search function somewhere in one of the menus, but can't remember which one.

We've all been there. Now there's a better way. The Navigator Assistant in IC61 was designed to overcome the frustrations of situations like these (and many others). Just select Window->Assistants->Navigator (or click the right mouse button (RMB) near the top of the design window and select Navigator). The Navigator Assistant will appear docked at the side of the schematic canvas. It displays the design hierarchy in a tree representation.

"That's nice", you say, but what does that get me?

Remember that sub-block you were looking for, but couldn't remember where it lived in the hierarchy? Now all you have to do is click on the little plus signs ("+") next to any of the listed design blocks to expand the tree underneath. Do this across as many levels as you need to find what you're looking for. What can you do now that you've found it? Click RMB->Open Instance... to open that cellview without having to open any of the intermediate levels.

Remember I44.I23.I0.I25.NM2? Well, look at that...now you can easily see which one is I44, even from 30,000 feet up. Just as easily you can find I23, then I0, then I25. RMB to open I25. Right there in the Navigator, you can see NM2. Click on it to select it (you did notice that selecting something in the Navigator cross-selects it in the schematic canvas, didn't you?). There you go...5 clicks, no zooming, no panning, no pushing or popping.

Extra Navigator Tips

You can use Shift-click and Ctrl-click to select multiple items in the Navigator, just as in most PC applications.

If you are zoomed in on an area of the schematic and you select an instance in the Navigator which isn't currently being displayed, the schematic will automatically pan over to show what you just selected.

You can add additional columns to the Navigator display such as Library Name and Lock Status (who is currently editing each cell and on which machine) by clicking RMB on the gray column header.

Notice the "Name" field at the top of the Navigator. It's actually a special field that you can customize. RMB anywhere below the gray column header and select Options... The top section of the Options form allows you to customize what gets displayed in the Name column of the Navigator to make it easier to read.

At the bottom of that Options form, you can set the default behavior when you execute the shortcut "Open Instance" command from the RMB context menu (edit/read, current tab/new tab). For example, I always like to open sub-blocks in a new tab so I can easily switch between them.

Finally, the Navigator traverses the design hierarchy based on a default view name list. If you routinely use view names other than "schematic", for example, you may need to change the view name list to get the Navigator to display properly. The view name list can be found under Options->Editor... in the schematic banner menu. Of course, view name switching can also be controlled from the Hierarchy Editor and the Navigator display will be updated automatically.

What Else?

Lots more information on the Navigator can be found in the Virtuoso Schematic Editor XL User Guide. There's also a nice video demonstration of the Navigator in the Virtuoso Custom IC Video Library on Sourcelink.

What's Next?

Stay tuned to this space to see how to teach an old dog a new trick.

Stacy Whiteman

Things You Didn't Know About Virtuoso: Tabs and Bookmarks

stacyw — Tue, 19 May 2009 13:00:00 GMT

Do you remember the first time you used a browser with tabs? All of a sudden, there you were...surfing two, three, four websites at once in the same window. Yee-haw! Life is good. Well, now you can do the same thing in Virtuoso. Okay, so you can't put YouTube in one tab and your schematic in another (yet), but you can easily have multiple tabs with schematics, layouts, symbols, etc. all in the same window.

No more minimizing and maximizing all your windows to switch between cellviews (is it this one? no, maybe this one? how about that one?). No more pushing and popping just because you don't want to open yet another window to take a quick look inside a block. Just stick it in a new tab and click over to it whenever you need to.

So how do you get these magical tabs to appear? Take a look at the forms that pop up when you descend into a sub-block of your design or when you do File->Open... from a design window. You'll see a radio button that offers you the choice to open the cellview in a new tab, current tab or new window. Give it a try.

Well, now that you've got all your favorite cellviews opened neatly in tabs in a single window, you'd like to be able to come back to this same configuration some time in the future. Of course, that's what bookmarks are for! Go up where you see the cellnames on the tabs near the top of the window and click the right mouse button (RMB). Select Add Bookmark... Alternatively, select File->Bookmarks->Add Bookmark from the top banner menu. You can bookmark just the design in the current tab or create a composite bookmark of all tabs in that window. You can even give it a name and a description to remind yourself what you bookmarked.

To use your bookmarks later, just select File->Bookmarks from either the CIW or any design window and click on the desired name to open it. No more scrolling through the Library Manager again and again to open each design one by one. You can organize your bookmarks by selecting File->Bookmarks->Manage Bookmarks from the CIW. There's even a Bookmarks Toolbar (RMB in the area near the top of the design window) for those designs you want to have available with a single click of the mouse.

This isn't meant to be a complete tutorial on how to work with bookmarks in Virtuoso. You probably already use bookmarks every day in your web browser, so using them in Virtuoso should feel pretty natural. If you'd like more information, refer to the Virtuoso Design Environment User Guide, which dedicates most of Chapter 11 to the subject.

You can also watch a video demonstrating the use of bookmarks, as well as some of the features I mentioned in my previous post in the Virtuoso Custom IC Video Library on Sourcelink.

Stay tuned to this space for more Virtuoso tips, because there are always things out there that you didn't know...

As always, feel free to share comments or suggestions or your own tips and tricks.

Stacey Whiteman

Don't Confuse Primary With Only

NewYorkSteve — Thu, 14 May 2009 13:01:00 GMT

Given the small nature of the EDA industry, I have read with some interest company announcements regarding "Primary" or "Key" EDA partnership status. In reading the content, it became clear to me that the wording was meant to obfuscate some important facts, particularly in the area of analog design which I work in. One might read those press releases and *think* that the quoted customer used only one EDA vendor's software for all their design needs. Or perhaps by "omission", the reader would be expected to make certain "assumptions" that were not true. That is why it was important for me to ask our customer SANYO Corporation to help "set the record straight". They have done so and you can read more by following this link. They are using Virtuoso IC6.1 combined with their extensive design expertise in the area of analog and mixed-signal design to help differentiate themselves from their competitors. Analog and mixed-signal design will differentiate the world's semiconductor companies from each other and help guarantee the strongest survive this economic turmoil. On a related note and just in time for CDNLive! EMEA, I am pleased to announce the completion of the 70th tape-out by our leading European customers using Virtuoso IC6.1.

Cadence has served the needs of the analog design community for 20 years and we will continue to innovate and serve in the years to come. That longevity allows us to set the standard by which all other EDA vendors in this space are judged, which if you think about it, I guess that makes Cadence the "Primary" vendor of analog and mixed-signal EDA design tools even if we are not the only EDA vendor in the world. I look forward to setting the record straight at more accounts.

Steve Lewis

Things You Didn't Know About Virtuoso: Introduction

stacyw — Tue, 12 May 2009 13:00:00 GMT

A while ago, I somehow ended up on the mailing list of a rather odd catalog called "Things You Never Knew Existed..." I think I got on the list when I bought some stocking stuffers for my kids for Christmas-things like little plastic pencil sharpeners shaped like noses (yes, you have the right mental picture-quite the hit with the 12-year-old set). So now you where to go to get a remote-controlled skunk or a USB hub that looks like Darth Vader.

So, you're probably wondering what this has to do with Cadence Virtuoso software. The thing is, I find in working with customers, I often show them things in IC 6.1 which cause them to say "Wow, I never knew that existed!" It seems that those clever R&D engineers here at Cadence have been putting so many great features in the software that it's hard for anyone to keep up. And, unlike the items from the catalog mentioned above, THESE THINGS ARE ACTUALLY USEFUL!

In this space, I'll be doing a series of short articles about some of these features. I'm a member of the CIC Core Comp team specializing in front end environment tools (i.e. Virtuoso Schematic Editor, Analog Design Environment and ViVA). Most of the features I'll be telling you about are available in the XL level of the tools (after all, that's what all the cool designers are using...), but some of them (such as today's tips) are available at all tool levels (L, XL, GXL). All of them are available today in the latest IC 6.1.3 ISR. Some of these features you may already know about and use daily, but hopefully you'll learn about a few new ones along the way.

Today's Tip: Opening Files
For today, let's start with something simple. What's the first thing you do after you start Virtuoso? You probably go to the Library Manager and scroll through that long list of libraries (you've been meaning to clean up your cds.lib file, but haven't gotten around to it, right?) and that long list of cells (with such easy-to-remember names as blk1v2xmem_a4 or was it a5?) to find the one you were working on yesterday. You click on the Library Name, then the Cell Name, and then finally double-click on the View Name to open it. Let's see, that was 4 mouse clicks (6 if you include opening the Library Manager).

Well, in IC6.1, you can do it the same thing in only 2 mouse clicks, and save yourself most of the mental exertion of trying to remember the name of the right cell. You see, Virtuoso now remembers the cellviews you most recently opened, just like your favorite PC application does. Go to the File menu of the CIW and you will see them listed there, right in the middle of the menu. The one at the top of the list (labeled 1) is the cellview you opened last and the others are listed in the order in which you last accessed them. Just click on the one you want and away you go.

If you want to get a bit fancier, you can tear off the File menu, stick it over to the side of the screen and click on the cellviews to open them whenever you need them. You did know you can tear off menus, right?-click on the dashed line at the very top of a menu and see what happens.

Bonus Tip
Speaking of the CIW, for those power users out there, did you know that in IC6.1 the CIW works a lot like your UNIX command line? You can use the arrow keys to cycle through your previously entered commands or type "history" to get a list of past commands (including logfile command output) and double-click to re-execute them. You can also cut and paste whole chunks of Skill code into the input area instead of doing it one line at a time. Give it a try...

What's Next?
That's just a little tidbit for now. For an even more powerful means of managing the cellviews you use most frequently, you may want to bookmark this page and check back again later...oops, did I just say "bookmark"?

How about you? Have you unearthed any hidden gems in Virtuoso that you‘d like to share?

Stacy Whiteman

Jurassic Park IV: The Return of ANALOG

NewYorkSteve — Tue, 05 May 2009 13:00:00 GMT

In the lab, no one can hear you scream!

When I was getting my BSEE in the 1980s and studying analog and communications, my friends would say, “Why are you studying that old dinosaur, digital is where it’s at!”. Well, far from being consigned to the La Brea tar pit, analog is once again on the upswing as companies seek ways to differentiate themselves in the marketplace. Over the last several months, I have been reading commentary (most notably from Texas Instruments) and listening to editors talk about the importance of analog and mixed-signal design to propel the electronics of the future which rely heavily on being able to interact with people, who are classically analog.

The difficulty with analog is a time-honored tradition, literally and figuratively. Analog, RF and strongly-analog mixed-signal design, all require a longer design time due to the hand-crafting involved. Classic digital design benefits from both uniformity of design and the homogeneity of cells so that the ability to synthesize a design is relatively easy, and the ability to create millions of transistors designs with full verification is an everyday occurrence. But an RF component of two dozen transistors can take a month to realize as part of the overall chip design. It is this time scaling that presents one of the larger challenges for doing mixed-signal design. At Cadence, we are lucky to have both extensive and strong technology in all of the disciplines that are required to do proper mixed-signal design. And given our breadth, we are also well positioned to bring together the best in class design methodologies in each of those domains to form the leading mixed-signal design solution. The Virtuoso group takes ideas from both the Incisive and Encounter groups to look for opportunities to speed up the analog portion of the design, while maintaining the accuracy required. From Incisive we learn the best ways to handle textural design elements, using compiled databases to speed the simulation, and using test vectors during the verification phase of the design. From Encounter, we learn the best strategies for designing for low-power, and how to combine routing and placement automation with the “assistance” in both of these areas demanded by the “hand-crafters” in the analog space. Combine this breadth of technology with Cadence’s 20 years of experience providing complete analog solutions to the electronics industry allows our analog customers to be the T-Rex’s of their company.

So, give a good roar…and try to keep the belching to a minimum.

Additional Reading:

Steve Lewis

An Efficient and Fast Verification Flow for Analog Designs Validation using Virtuoso SpectreMDL

helenet — Mon, 04 May 2009 13:00:00 GMT

The emergence of sub-micron technologies has enabled today’s designers to include various digital/analog/RF components in a single chip. The complexity of validating such designs has highlighted the necessity for a robust validation methodology and for an appropriate process for running efficient simulations. At CDNLive! 2008, we introduced will an innovative, efficient and accurate verification flow using Cadence Spectre Measurement Description language (MDL) and explored the strengths and advantages of this flow using IBM environment. This paper exhibited how having such a re-usable, unified and automated simulation environment has significantly improved validation productivity and efficiency, guaranteeing a higher quality of verification for IBM analog designs. Validation of IBM flows and environments using spectreMDL were explored at various levels:

Process technologies validation
Statistical analog cell characterization
Analog circuit analysis specific characterization requiring higher-level control/complexity

Using this flow, capability to execute advanced and complex measurements and run intelligent corner and statistical simulations using Cadence SpectreMDL scripting language was fully demonstrated. Minimal testbench development time while maximizing functional coverage was proven using this methodology by highlighting the portability and re-usability of this flow for several IBM analog designs and characterization of ASIC libraries at 65 and 45nm.

Top Takeaways:

Vast Simulation efficiency and speed improvement using spectreMDL for functional verification
Capability to perform complex measurements and run advanced analysis without modifying original designs
portability and re-usability of spectremdl scripts among various designs and technologies

Helene Thibieroz

Getting a Feel for RF

TomC — Wed, 29 Apr 2009 13:00:00 GMT

It was a delight when I read the blog by Bill Schweber of TechOnline's RF DesignLine titled “Getting some basic RF experience”. I was surprising pleased that somebody took the time to talk about how one might get the feel for RF. That is because what Bob talks about is more or less how I gained some of the experience that lead me to pursue this decades later.

I have always been fascinated by radio in one form or another. It started when I was youngster listening to an AM radio and found that there was a huge difference in the number of radio stations I heard in the daytime versus the number I heard at night.

Without knowing it I was learning about sensitivity, selectivity, propagation, adjacent channel interference, ambient noise, bandwidth, antennas, modulation and the effects of solar radiation. Through my ears I heard the effects of all of these characteristics and hardware. All of this courtesy of a 1960’s vintage Sears Silvertone, ten-transistor desktop radio.

Later on using a pair of crystal controlled citizen band (CB) transistor walkie-talkies in the late 60’s, I discovered more about antennas, range versus power and elevation, jamming other radios (purely by accident and would serve me well later while working on electronic counter measures), power supplies, what small increases in voltage would do to power out and what too much voltage and power would do to a transistor. This would later in life open the door to an education in electrical engineering and amateur radio. What does this have to do with a blog at Cadence? Plenty.

Simulation provides an avenue for engineers to experiment with designs and sharpen expertise by trying various circuit designs and subjecting them to the environment they will eventually be operating in. When I talk about exploring my ideas and designs, I’m talking about using Virtuoso, SpectreRF and Analog Design Environment (ADE).

I’m lucky in the fact that my employment here puts me in close proximity to these tools everyday, and I often take advantage of it. Because my designs are no longer fabricated in silicon, the capabilities may be a bit more than I need.

Through a virtual test bench in ADE and simulation using SpectreRF one can get a feel for how RF circuits work, testing their susceptibility to variations in component values, which elements in the circuit actually changed the performance versus the ones that limited RF leakage back into the power supplies. One could see how the impedance (load) of one stage or block presents to the next block and so-on. The designer could get a feel for the effects of parasitics on the design. While designing an RFIC it is a lot more than what I described, the basic concepts are still the same.

Whether the results are on a PCB or in silicon, to me it still comes down to getting a feel for the RF either at the bench or through an environment where I can control the simulation, and then see the results. Simulation provides insights well in advance of probing the design on the bench.

For me it was not only the math and physics of it all, but experimenting and playing with the designs. It still is.

Tom Costas

OpenAccess, Its Just a Database…

TomC — Mon, 20 Apr 2009 13:00:00 GMT

I suspect that in another year we’ll all stop talking about OpenAccess (OA) like it is something special and treat it the way it should be, that it is just another database. Having said that, I know I’m going to get plenty of email about my portrayal of OA from colleagues and others but that is the way I see it.

Let’s not fool ourselves, today OA is a big deal because it truly is a different way that will allow designs and design information to be portable between applications from the same or different vendors without the need import and export data that loses intelligence in the translation. It is as simple as that to the users.

The motivation behind all of this is to have an “open” standard for IC design information and to get it adopted within the EDA industry. These goals are defined by the OpenAccess Coalition* which seeks to provide its partners with technology and support that will:

Provide tight integration and incremental design flows using design tools and data from multiple sources
Ease integration of internally developed tools with those from EDA suppliers
Provide more cost effective technology transfer of university research into the design flow
Simplify technology sharing for collaborative development between business partners for design tools and design data

It is intended for industry-wide interoperability where OA will permit companies to create flows utilizing design tools from different EDA vendors to best suit their individual and custom needs. Cadence, along with others, is moving forward with OA. Some have announced their intent to support and use it, while there are plenty more poised to do the same. I foresee that in the next twelve to eighteen months we’ll see more EDA companies accessing design data and provide interoperability via OA. I think a bit of history will help put some of this into perspective.

As reported in 2002 by my colleague here at Cadence, Richard Goering, OA Version 1 database code was released to the coalition in February 2002 by Cadence. It was originally known as the Cadence Genesis code which was intended for digital designs. Later in June of 2002 Version 2 was released and it now had support for analog and mixed-signal designs along with technical features to facilitate support by developers. OA was now fully in the public domain courtesy of Cadence. At that time there was only two other members of the OpenAccess Coalition. The OpenAccess Coalition has come a long way since then.

One last thought before I wrap-up. There have been some recently noted comments saying that OA is only good enough for custom IC design but not digital. How can this be?

Didn’t I just get finished saying that it is “truly is a different way that will allow designs and design information to be portable between applications”. And didn’t I quote the OA Coalition in saying that this would, "Provide tight integration and incremental design flows using design tools and data from multiple sources". We, Cadence that is, took “multiple sources” to mean from different tools addressing differing design domains.

I beg to disagree with those making this claim. OA is a design database for representing information regardless of the design type. Our digital tools prove it. Encounter reads OA and writes OA. Virtuoso reads OA and writes OA. Virtuoso exchanges information with Encounter via OA. OA carries both the analog and digital design information.

Back to my premise which is OA is big news now, and Cadence along with others will talk it up but it will fade into the background and simply be the database of design going forward. I like to think that it will allow you to “Create, collaborate, and just build it.”.

Tom Costas

*Bulleted items are taken directly from the OpenAccess Coalition website found at www.si2.org.