( DAC'20 Item 1d ) ------------------------------------------------ [02/12/21]
Subject: EMX/Spectre-RF/Virtuoso-RF combo 75% easier use is Best of 2020 #1d
THE ACQUISITION THAT WORKED: I'm proud to say we have our first ever EMX
user review in this report. (Getting RF guys to talk on anything is rare;
in the chip design world these folks are much closer to Maxwell's Equations
than the digital guys ever were.) Anyway, these particular RF guys were
happy EMX users, but when Cadence acquired Integrand, their fears hit home
for any EDA user:
"... we were nervous when Cadence acquired Integrand -- we worried
that our little tool that made us so successful (EMX) would die
a slow death swallowed up in a big company."
It's an age old drama in EDA. But what happened next was *very* unexpected:
"Cadence immediately gave us their EMX roadmap -- and asked us for
input -- which, to our shock, they *actually implemented*."
"In the months since then, Cadence R&D stitched EMX into both
Spectre RF & Virtuoso RF extremely well. The process of
extracting and running EMX on our designs is now ~75% easier
than it was before the acquisition."
This "happy about inter-tool integration" story backs some of what Anirudh
said on my Troublemaker Panel (ESNUG 588 #24) on how Cadence is going to
steal marketshare from Ansys with his 3D-IC strategy.
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BONUS SCOOP! My spies report that Tom Beckley's analog EDA R&D guys have
a distributed massively parallel Spectre-RFX in the works -- something that
none of the other SPICEs for RF do! (See user comments below.)
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QUESTION ASKED:
Q: "What were the 3 or 4 most INTERESTING specific EDA tools
you've seen in 2020? WHY did they interest you?"
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We are RF developmers. We've used Cadence Spectre-RF and the
Integrand EMX solver/simulator for over 5 years now. (Anirudh
bought EMX in 2020.) In addition, we are just starting to use
Cadence Virtuoso RF environment (versus just Virtuoso).
This is our experience with all three products.
CDNS Integrand EMX
The EMX solver became our gold standard for 5 years, after we first
spent a few months confirming that our models matched the EMX results.
Now we load our EMX generated S-parameter files into Spectre RF for
simulation.
- Every single one of our RF chips has come out working on the
first pass for the 5 years now -- this is rare for RF chips.
- I give EMX a lot of credit for this, plus the rigor of our
engineers who were proficient at using it.
EMX worked so well for our RF chips that we were nervous when Cadence
acquired Integrand -- we worried that our little tool that made us so
successful (EMX) would die a slow death swallowed up in a big company.
The good news is that Cadence's support and integration of EMX has been
outstanding.
Before Cadence's Integrand acquisition, we used EMX with Cadence
Virtuoso and Spectre-RF "on the side". We would:
- Use Virtuoso for our layout, i.e. draw our inductor and the
rest of circuit.
- We'd take our inductor layout, give it to EMX, along with the
frequency, temperature, and metals used. We'd run EMX to
extract the inductor parameters and generate the S-parameter
file.
- Then we would *manually* reference the S-parameter in our
Spectre-RF simulations.
After Cadence bought Integrand, Cadence immediately gave us their
roadmap -- and asked us for input -- which, to our shock, they
*actually implemented*. In the months since then, Cadence R&D
stitched EMX into both Spectre RF & Virtuoso RF extremely well.
The process of extracting and running EMX on our designs is now ~75%
easier than it was before the acquisition. This translates to huge
efficiency and stress reduction for our engineering team.
Our engineers usually resist change, but these improvements were
so good that they decided they also wanted to buy Virtuoso RF.
(Details on Virtuoso RF are below.)
I've used EDA tools for IC design for decades. Rarely have I seen
this level of cooperation. Kudos to the EMX and Cadence R&D teams.
Some EMX features, including a Cadence improvement.
- A black box capability. Once we use EMX to solve for a
particular inductor, a knowledgeable user can enter the
result for that inductor so that EMX doesn't re-solve it.
- We can take a waveform that comes in and manipulate, modulate,
and change it using passive and active RF components to do what
we need it to do.
- Message Passing Interface (MPI). Cadence R&D has added MPI
capabilities for EMX. It lets us run EMX on multiple computers
and pass information. The pieces need to know about each
other, e.g., System "B" needs to know information on System "A".
(Spectre RF already had an MPI)
- Before: We could run EMX on a computer with 40 cores for
speedup.
- Now: We can run EMX on 5 computers with 40 cores each.
And the computers can see each other's disk drives.
The disk is mounted across the environment. EMX automatically decides
how to break it up. (Each segment can differ in size so the speed up
for 5 computers is not necessarily 5X). We are just now getting this
version installed.
Spectre RF
Spectre RF is an option to Spectre for simulating RF circuits. It runs
like Spectre but has extra functions -- e.g., we use it for Shooting
Newton PSS (Periodic Steady-State) analysis and harmonic balance.
You can run Spectre RF on your IC, as well as on your PCB and packaging.
We use it for our ICs only; in particular, to simulate our inductors
and RF circuits.
We create complex high speeds designs from scratch. We typically run
both Spectre RF and EMX on 40 cores.
- Our Spectre RF simulations can take up to 1 week to run on
compute farms.
- Our EMX runs take about the same amount of time as Spectre RF.
We make sure we cover all our bases.
Virtuoso RF
Virtuoso RF is a visually integrated RF environment for EMX, Quantus
(RC extraction), and Spectre RF. It has a model assistant to let
you to extract S-parameters from your nets and multiple instances
in your Spectre RF simulations.
Virtuoso RF has advantages for RF design over Virtuoso. For example,
- In old Virtuoso only (not Virtuoso "RF"), if we only want to
simulate a portion of our RF design, we must manually create
different cell views and hierarchy in old Virtuoso for that
portion of the design. This set up would take us a few hours
every time.
- With Virtuoso RF, we can simply point to that portion of our
design layout and then run Quantus and/or EMX only on that
piece. Virtuoso RF automatically takes care of creating the
right cell views and hierarchy.
We typically design our RF IC and send the artwork to our PCB designers.
They create a footprint, populate it to the PCB, and then the PCB goes
into bigger system, such as a control module. Problem is we ultimately
lose track of our RF IC and where it goes after tapeout.
Our team focuses on the RF IC, but with Virtuoso RF can do much more.
We can use Virtuoso RF to:
- Place our IC on your PCB using Allegro.
- Bring our PCB into view and zoom into our RF IC and its
internal structure.
- Trace a signal within our RF IC and follow it to a pad outside
of the IC. We can trace it along the PCB and follow it as
far as we want -- as long as data is within Virtuoso RF.
We can even crossover and dive into another IC on our PCB.
That signal tracing is very important to me. I have a circuit that
describes the system -- and it's important to simulate the signal
that I traced in Virtuoso RF.
I also like that I can also use Cadence's Clarity 3D solver with all
the data from EMX and Spectre.
The bottom line is that you can get all the characteristics you need to
model your signals for Spectre RF. EMX completes Cadence's series of
tools that let you do this.
Our engineers are not big on any workflow disruptions. But Virtuoso RF
has evolved -- and the integration of EMX alone took us over the wall so
our engineering team embraced it. It's not that hard to learn and makes
our job much easier.
Cadence Support
Our local Cadence support does an outstanding job. They are willing to
answer questions and provide one-on-one training. If they don't know
the answer, they will find it for us. We ask hard questions, and they
are tenacious in solving our problems.
For example, for Virtuoso RF, they gave us an online demo. There were
only a couple things it couldn't do that we needed. Cadence came back
and implemented them. We did *not* expect that -- it's pretty amazing.
We are now in the process of installing Virtuoso RF and setting it up
for our RF design team.
I would definitely recommend EMX and Spectre RF. Cadence biggest
strengths for them are EMX's golden accuracy and the integration.
We are just now beginning to use Virtuoso RF. So, although it's too
soon to recommend it, I'm expecting it will take that integration to an
even higher level.
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RUMORS OF A DISTRUBUTED SPECTRE-RFX
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We are quite interested in the new Spectre RFX simulator. It has
massive parallelism plus accuracy for harmonic balance methods.
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Look at Spectre RFX.
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Beckley's guys are working on a distributed HB Spectre.
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