( ESNUG 503 Item 7 ) -------------------------------------------- [05/04/12]
Subject: Readers question Jim Hogan's SPICE rankings and math accuracy
> Cadence continues to dominate the Analog and RF simulation markets, with a
> strong presence in the mixed language side of the mixed signal market,
> while Berkeley Design Automation (BDA) competes with Cadence for market
> share. ... Mentor Eldo is down to just one top-20 semiconductor company
> so is unlikely to be a significant factor.
>
> - Jim Hogan of Vista Ventures LLC
> http://www.deepchip.com/items/0502-08.html
From: Linda Fosler <linda_fosler=user domain=mentor got calm>
Hi John,
Recently Jim Hogan posted his opinion on analog SPICE simulators (amongst
other things). Here's Jim's list in his view of analog market prominence.
Analog: 1st- Cadence Spectre, APS
2nd- BDA AFS
3rd- Agilent GoldenGate
4th- Synopsys HSPICE
5th- Mentor Eldo
Where did the data for this list come from? Yes, #1 is probably Spectre;
but HSPICE at 4th? And Mentor at 5th? BDA with 2nd order position? And
Agilent is even on the list?
A real list for analog SPICE looks like this:
Analog: 1st- Cadence Spectre, APS
2nd- Mentor Eldo
3rd- Synopsys HSPICE
And the rest don't make the cut.
- Linda Fosler
Mentor Graphics Corp. Wilsonville, OR
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> ... The ideal meta-simulator for memory design addresses their key
> challenge: measuring yield-performance tradeoffs out at 5 or 6 sigma,
> with the same accuracy as millions or billions of Monte Carlo SPICE
> simulations but with a low computational cost. ... and it looks like
> the first SPICE killer app is Solido High-Sigma Monte Carlo (HSMC).
>
> - Jim Hogan of Vista Ventures LLC
> http://www.deepchip.com/items/0502-08.html
From: [ Doubting Thomas ]
Hi, John,
I have a deep and long-held respect for Hogan, spanning decades. But I
believe he's dead wrong on this Solido HSMC tool. How can the tool
guarantee "5 or 6 sigma" when the underlying SPICE simulator cannot?
The answer they give is they assume the simulator is perfect, shows a
fundamental gap in reasoning and a need for remedial statistics classes.
- [ Doubting Thomas ]
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From: [ Curious George ]
Hi, John,
Solido claims their HSMC tool gets 6 sigma accuracy, which is 99.99966%,
or 3.4 defects per million. There are two problems with this assertion:
1.) SPICE models of physical effects are, at best, models. Even
with 3D extraction, approximations of geometries are used.
Real etched wafers have warped, smoothed uneven shapes and
edges. At best, with first-order and second-order effects
taken into consideration, device models will get within
2% or 3% of real silicon; nothing near the 99.99966% Solido
needs to be 6 sigma.
2.) SPICE simulations are not computed with infinite accuracy
on a computer. They typically involve floating point numbers
of maybe 6 or 8 significant digits. Do the 5 billion SPICE
runs Solido claims and they will again be nowhere near the
99.99966% needed to be 6 sigma.
It appears Hogan has a misplaced (and mathematically impossible) pride in
his 6 sigma Solido investment.
- [ Curious George ]
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