[SI-LIST] Re: SpecctraQuest
- From: "Lynne Green" <lgreen22@xxxxxxxxxxxxxx>
- To: "'Si-List'" <si-list@xxxxxxxxxxxxx>
- Date: Thu, 6 May 2004 17:17:27 -0700
Both HyperLynx and SpecctraQuest (Allegro SI) have added new features,
including support for "GHz simulation" and an HSPICE interface.
If you are planning to use S-parameters for interconnect models, IBIS 4.1
(VHDL-AMS or Verilog-AMS), or have other advanced requirements, you should
definitely talk to the respective vendors about if/when/how your
requirements would be supported.
If you are creating IBIS models, then the Cadence SPECCTRAQuest Model
Integrity module is nice. (HyperLynx does not have an equivalent.)
Both tools are suitable for model validation.
As Kai mentioned, the Cadence tools are designed to work together, from IC
and package design to layout to SI simulation. On the other hand, if one is
using a mix of point tools, one can take advantage of HyperLynx's
translators to use layouts from various layout tools.
- Lynne
Dr. Lynne Green
Green Streak Programs
http://www.greenstreakprograms.com
425-788-0412
lgreen22@xxxxxxxxxxxxxx
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Kai Keskinen
Sent: Thursday, May 06, 2004 4:05 PM
To: Si-List
Subject: [SI-LIST] SpecctraQuest
I've been following the discussions regarding which tool is best with great
interest. I have been a Cadence SpecctraQuest user for many years and I
haven't seen anyone comment on the tool properly. I'd like to do so now:
If your board file is in the Cadence environment and the company component
libraries are also done with Cadence, the Cadence tool flow provides a
complete solution from schematic capture to post-layout analysis where
constraints can be entered at almost any point and back annotated. My first
exposure to SQ was in a company using the entire Cadence tool flow. Other
company's tools also provide similar solutions. Cadence has continued to
improve the integrated tool flow and it is very powerful now.
I'm currently working for a design services company where we perform either
pre-layout analysis to provide layout guidelines and/or we do post-layout
analysis including static timing. We started with another EDA vendor's tool
which promised much but had lots of bugs, crashed on complex designs, and
had a horrible user interface where you could not even cut and paste from
menu to menu. To do anything quickly, you had to write scripts. On the plus
side, its documentation was good. As well, to get their exploratory tool,
post-layout analysis tool, and multi-board option, you had to pay much more
than SQ which comes with all three features. We then moved to SQ which is
not a low budget tool but is well worth the money if you will be using the
license at least 40% of the time. Avoiding 1 board respin more than pays for
the initial price for the tool. The yearly maintenance is well worth the
money.
SQ has import capabilities from many other layout tools. We have used it
successfully with only minor issues from several of the other major layout
tools. Cadence will help if the translation fails.
SpecctraQuest, like most SI tools, is based on a spice engine and uses IBIS
models. We have used SQ for simulations up to 3.125Gbps with good
correlation to hardware measurements. If you have a spice license, you can
simulate using one of several commercially available spice packages
including HSPICE if you only have spice models of devices.
As with almost all board level tools, you set up the board, define passives
and enter your device models. SQ provides a handy board set up advisor that
walks you through the process. You can then perform reflection and
cross-talk simulations in the board file. The tool provides a number of
standard measurements such as flight time, switching time, overshoot,
settling time, etc. You can also define custom measurements. Standard and
custom reports on the simulations can be easily exported in text format so
you can bring them into a spread sheet. The waveform viewer is quite
powerful and gives you standard scope view, logic analyser (or bus view),
frequency domain view, and eye diagram view. You can use custom bit
sequences in simulations as well as random ones. You can import HSPICE and
some other tool outputs for comparisons. You can set the scale on the
vertical and horizontal axes to what you want and not just a few fixed
scales like some other tools.
One of the best features of SQ is the SigXP tool which is a blackboard type
exploratory tool where you can do pre-layout analysis and then capture
constraints electronically for the Cadence tool flow and paper (or virtual
paper) for other layout tools.
SigXP allows you to create different lossy transmission line geometries
including multiple coupled lines (both broadside and edge coupled) and then
use them with your IBIS device models. This means it has a built in 2-D
field solver. As well, if you have a board file, you can extract via models
and use those in pre-layout simulations for other boards with similar
stackups. You can now easily perform cross-talk simulations in SigXP.
One of the best features of SQ is the extraction feature which allows you to
extract a routed net from a board (or the manhattan lengths for an unrouted
but placed board) into SigXP and both view and simulate it. The extraction
lets you quickly see what is wrong with a net that gives poor simulation
results or for trouble shooting a board that is in the debug state.
Once you are familiar with the tool, you can complete a post-layout analysis
for a simple board in a few days while a complex board may take a few weeks.
The learning curve for the tool is somewhat steep if you are on your own.
The best way to learn is to get some tutoring from a more experienced user.
The documentation is complete but if you don't know what can be done, you
have trouble finding how to do it in the documentation. The Cadence support
line is excellent with speedy response and very knowledgeable support staff
(most of the time). They also provide courses like all of the vendors. The
SourceLink web site (you need a valid maintenance agreement) is very good
and the free SpecctraQuest web site is also useful.
All tools including SQ have bugs. Cadence takes problem reports seriously
and fixes the bugs quickly or provides workarounds until the next release.
If you want to evaluate SQ, Cadence will usually give you a temp license for
a long enough time to get a feel for the tool. The best way to do this is to
have a project and the time available to properly try the tool.
If anyone wants any more input on the tool, please send me an e-mail off
line.
Regards,
Kai Keskinen
kalevi@xxxxxxxxxx
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