( ESNUG 515 Item 1 ) -------------------------------------------- [11/29/12]
From: [ Jim Hogan of Vista Ventures LLC ]
Subject: Hogan on the early days of Custom 1.0 and Cadence Analog Artist
Hi, John,
When I started my semiconductor career in the late 1970's, custom circuit
designers optimized their circuits to transistor electrical and physical
models. The final resulting design was then handed off to physical layout
technicians. This process was very tedious and error prone.
Because of this handoff, a lot was lost in translation from designer to
layout technician.
CUSTOM 1.0
The first era of custom design, or what I'll call "Custom 1.0", began around
1980. It focused on a simple workbench to improve a circuit designer's
productivity. This crude, initial approach (Analog Artist) used schematics,
tied to SPICE simulation, and then annotated its results to the schematic.
There the design could be probed in-situ and analyzed further with apps such
as a wave form tool and a calculator.
Though it may seem trivial now, at the time it was a tremendous boon to
analog designer productivity and circuit optimization. SPICE engines at the
time were still mostly very close cousins with UC Berkeley SPICE -- in
general they ran on mainframe computers and were written in FORTRAN.
There's since been tremendous advancements in visualization capabilities,
pure compute power, and the SPICE simulation engines themselves.
EARLY HARRIS SLICE
In its early days,"Cadence Analog Artist" was really a rough, first cut
analog environment that came from Harris Semiconductor and was called:
SLICE - Simulation Language with Integrated Circuit Emphasis
The Harris SLICE team was led by James Spoto. Harris wanted Cadence to
commercialize it.
That's where Jim Solomon, who has always been one of my heroes, stepped in.
Jim started SDA/Cadence in 1983; he was a renowned analog designer who had
previously led Motorola's analog design team and National Semiconductor's
analog design team. Jim made the case that Cadence could develop and
market a full custom design environment based on SLICE that met designers'
needs -- and was not totally focused on one specific point tool.
Once Harris signed on board, "SLICE" was quietly renamed "Analog Artist" to
make it more marketable.
  
Both Jim and James are first and foremost analog designers, and as a result
Analog Artist was much more of a gray box approach than a digital black box
approach. Their philosophy was that analog designers -- and for the matter
custom designers -- needed to *explore* their design space and *interact*
with their circuit design. (Something somewhat radical in the day of hand
drawn circuits analyzed by hand calculating equation with pencil and paper.)
SKILL
At first, the Harris team used an interpreted language called "SKILL" to
both create and interact with their in-house SLICE tool. Since it was
interpreted, it made early Analog Artist runs as slow as molasses. One
of the first things we did in Cadence was to immediately write a SKILL
compiler to speed up these run times.
Also initially SKILL was used for the electrical aspects of custom circuit
design. Then later in the early 1990s, SKILL was integrated with physical
layout. This SKILL integration let engineers extract physical parasitic
information that they could then back annotate into their electrical
schematic -- thus allowing human iteration/optimization of his circuits.
MARRIED TO THEIR SPICE
It came as somewhat of surprise to me, as marketing VP for Analog Artist,
that designers were very wedded to their SPICE simulators. They preferred
the familiarity of their favorite SPICE simulator over cost and features.
The headache for us at Cadence at the time was that Analog Artist was often
coupled with Meta Software's HSPICE, a UC Berkeley derivative -- even though
we had own UC Berkeley-derivative SPICE simulator. This was my first
experience with customer loyally to the best point tool even if it came
from another vendor.
There was a lot of stickiness in our analog design environment, but there
was also a lot of stickiness to 3rd party SPICE simulators.
It wasn't until Cadence introduced Spectre that we first saw some designers
who were willing to change.
BARRIER TO ENTRY
Cadence Analog Artist, recently renamed Analog Design Environment, is still
used very widely and remains an important Cadence franchise. Customers have
literally written millions of lines of SKILL code to adapt this environment
to meet their own unique needs.
The state-of-the-art computer science has advanced considerably in the last
30 years plus SKILL scripting doesn't offer the major advantages it once
did. Luckily for CDNS, that customer investment in personally customizing
their analog design environments has created a significant barrier for
competition to displace Cadence in custom design.
However, after looking at what exists now in the custom design arena, and
what the world is evolving to look like soon, I believe that custom design
is on the cusp of serious substantial change. We are entering a new era
where analog design tools simply won't cut it.
This is why, after 30 years, companies are now retooling for Custom 2.0.
- Jim Hogan
Vista Ventures, LLC Los Gatos, CA
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