Mar 2, 2011

SPICE: a 40-year old open-source success story

From EDN:

SPICE: a 40-year old open-source success story
SPICE, the Simulation Program with Integrated Circuits Emphasis, has turned 40 years old. The IEEE has marked the occasion by designating the development of SPICE as a Milestone in Electrical Engineering and Computing. On February 23rd, the Computer History Museum hosted a celebration with a roundtable discussion by the individuals most responsible for bringing SPICE from its origin as a UC Berkeley student project to the huge commercial success it has achieved as the most widely used tool in the semiconductor industry.
spice-panel-copy.jpg
The panel (from left to right) consisted of:
  • Ron Rohrer - 2002 Kaufman Award recipient, who taught the class at UCB that developed the progenitor of SPICE, CANCER (Computer Analysis of Nonlinear Circuits, Excluding Radiation)
  • Larry Nagel - as a student in Ron’s class, Larry took on CANCER as his Master’s degree project, and eventually developed the 1st successful implementation - SPICE2 - as his doctoral thesis.
  • Kim Hailey - co-founder (with Shawn Hailey) of Meta-Software, where HSPICE was created.
  • Ken Kundert - who led the development of Cadence’s Spectre simulator.
  • David Hodges - Distinguished Professor Emeritus at UCB, the panel moderator, who is well known for leading the development of analog IC design in CMOS and for the original (Level-1) Shichman-Hodges MOS device model.

Read more.... in EDN

Feb 28, 2011

Analog/Mixed-Signal Behavioral Modeling

From Cadence... (see the original)

Analog/Mixed-Signal Behavioral Modeling – When to Use What



So when to use what? The conservative style provided by Verilog-A and Verilog-AMS is useful when there are significant accuracy requirements. This approach can potentially provide a 50-100X speedup over SPICE, but it all depends on how good your modeling is. "If you're a poor modeler, there's a chance you could end up with a model that's as slow as SPICE simulation or even slower," Walter warned.
Real  number modeling, also available through Verilog-AMS with the wreal data type, brings real number values into event-driven digital simulation. It thus has the speed benefits of digital simulation and can leverage the metric-driven verification methodology that's increasingly used by digital engineers. It's good when there are hard performance requirements and limited accuracy requirements. For example, wreal is very useful for full-chip mixed-signal simulations.
The following chart shows the accuracy/speed tradeoff ranges provided by various analog/mixed-signal modeling alternatives. Note that the conservative modeling style has a broad possible range, depending on how good the modeling is.
Also important is the modeling effort. Here we can see that conservative models require the most amount of effort. "You can potentially spend days, weeks, months to develop good behavioral models," Walter said. Wreal models are relatively fast to develop because they're less detailed. An important rule of thumb: "Model what you need, not what you can."

Feb 25, 2011

Microelectronics Journal, in-press, february 2011

Modeling of threshold voltage of a quadruple gate transistor

Md. Gaffar, Sayed Ashraf Mamuna, and Md. Abdul Matina

Available online 24 February 2011.
Abstract

In this paper, a three dimensional analytical solution of electrostatic potential is presented for undoped (or lightly doped) quadruple gate MOSFET by solving 3-D Poisson's equation. It is shown that the threshold voltage predicted by the analytical solution is in close agreement with TCAD 3-D numerical simulation results. Numerical simulation, self-consistent Schrodinger–Poisson equations, calibrated by 2D non equilibrium green function simulation, are used.

Feb 23, 2011

The First Full-Color Display with Quantum Dots

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The First Full-Color Display with Quantum Dots
Samsung's new four-inch display could eventually lead to flexible screens.
By Prachi Patel

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SPICE Circuit Simulator Named IEEE Milestone

Simulating a circuit with SPICE is the industry-wide standard way to verify operation at the transistor level before manufacturing an IC. The program has become so ubiquitous that engineers often say they are going to “SPICE a circuit” when they are about to test one. To mark the 40th anniversary of SPICE—the Simulation Program with Integrated Circuit Emphasis—IEEE has designated its creation an IEEE Milestone in Electrical Engineering and Computing.

SPICE was made publicly available in 1971 so that chip designers could modify it—an early example of open-source software. Two years later, SPICE became well known after it was described in a paper by Pederson at the 16th Midwest Symposium on Circuit Theory, in Waterloo, Ont., Canada. During the next few years, developers around the world began using and modifying SPICE, leading it to become the industry standard it is today. “What happened was truly phenomenal,” Nagel wrote in “The Origins of SPICE.” “Within a few years, SPICE had achieved acceptance at almost all electrical engineering schools [for use in teaching] and had [spawned] a cottage industry to supply SPICE derivatives to the rapidly expanding integrated circuit industry.”

[Read more by Anna Bogdanowicz @ IEEE]