An Interview with Mike Engelhardt - SPICE Simulator Synteresis

The Amp Hour · 30 Apr 2014 · 1h 32m · Episode 196

What this episode covers

Mike Engelhardt, creator of LTspice at Linear Technology Corporation, explains how he built the world's fastest SPICE simulator by implementing self-authoring assembly code to run the CPU pipeline hot, bypassing the overhead of dynamic memory allocation. He details the technical differences between LTspice and Berkeley Spice, noting that LTspice’s half-million lines of code correct numerous convergence bugs and discontinuities found in the academic original. Engelhardt also discusses the challenges of modeling power MOSFETs, the development of specialized macro models for switch-mode controllers, and the strategic decision to keep LTspice proprietary to maintain Linear Technology's competitive advantage in IC design.

Mentioned

Companies
Linear Technology Corporation, International Rectifier, Infineon, NXP
Products
LM3780, LM741
Tools
LTspice, Berkeley Spice, P-Spice, H-Spice, KiCad

Other shows on the same ground, closest first.

  • Moore's Lobby · 55m

    QSPICE Circuit Simulation: A Spicy Discussion with Mike Engelhardt

    Mike Engelhardt, creator of LTspice and now QSPICE at Qorvo, explains how he built circuit simulation tools starting from his work in physics labs and oil exploration. He details the rapid development of LTspice in 10 months to serve as sales collateral for Linear Technology, emphasizing that simulation's primary value is building engineer intuition rather than just verification. Engelhardt then describes refactoring the open-source Berkeley SPICE code to create QSPICE, which fixes bugs in the sparse matrix package and leverages GPUs for waveform plotting rather than computation to handle wide bandgap semiconductors like GaN and SiC.

  • Embedded.fm · 1h 01m

    87: Make My Own Steel Foundry

    Chip Gracey, co-founder of Parallax, discusses the design and philosophy behind the Propeller microcontroller, a chip featuring eight independent cores (cogs) for deterministic real-time control. He explains the decision to open-source the Propeller One Verilog code to foster community learning and innovation, while detailing the complex, years-long process of designing the Propeller Two using SPICE simulation and custom layout. Gracey contrasts this first-principles approach with modern ARM-based systems, advocating for simplicity, transparency, and the ability to understand hardware at the transistor level.

  • Embedded.fm · 1h 04m

    356: Deceive and Manipulate You

    Leonardo Laguna Ruiz, founder of Vult and software engineer at Wolfram Research, explains how he models vintage analog synthesizer circuits digitally to run on microcontrollers. He details the process of deriving nonlinear differential equations from component-level schematics (like the Moog Ladder and Polivoks) and solving them using methods like Runge-Kutta to simulate filters and drums. Ruiz also discusses his custom Vult programming language, which compiles DSP code to C++ and JavaScript, and his Eurorack hardware product, the Freak Filter, which allows users to switch between these modeled filters.

  • Embedded.fm · 48m

    105: Some Paths Are More Suicidal

    Manny Wright, Senior FAE Manager at Cortus, explains the process of designing custom processor IP, from RTL to silicon fabrication. He details the high costs and long timelines (1.5+ years, millions of dollars) involved in tape-out, the role of FPGAs like the Xilinx Spartan in early development, and the importance of configurable cores for power and cost efficiency. Wright also discusses security features, debugging methods like JTAG and trace, and the challenges of protecting intellectual property from reverse engineering.

  • The Spark Gap · 57m

    The Spark Gap - Episode 29

    Dr. Fouad Kiamilev from the University of Delaware explains the design of application-specific integrated circuits (ASICs), detailing a high-power display projector chip with 250,000 I/Os and liquid nitrogen cooling. He describes the iterative development process, from a 64x64 test chip to a 512x512 production module costing $250,000, and the use of Cadence tools for full-custom layout. Kiamilev also discusses the importance of physical health, fitness, and work-life balance in sustaining long-term engineering productivity and avoiding burnout.

The summary, chapters and topics are generated from the episode’s audio by this directory, not written by The Amp Hour. The episode itself belongs to its publisher.