Qorvo's QSPICE Is a Free Next-Generation Mixed-Mode SPICE Simulation Tool

The first version of the general-purpose Simulation Program with Integrated Circuit Emphasis, or SPICE, was released in 1973. 25 years later, an engineer named Mike Engelhardt started work on a version of SPICE. And now, 25 years later, Qorvo introduced his latest work as QPSICE, a next-generation mixed-mode SPICE simulator.

"Basically, QSPICE is what I would have written 25 years ago when I wrote LTspice had I known then what I know now." — Mike Engelhardt

Over the past 50 years, engineers have written many variations and types of SPICE tools. Using them is straightforward. You create a circuit, give it some parameters, and it returns some values. Today's SPICE simulators have graphical front-ends and plotting tools. The critical difference between them is the types of circuits they analyze. For example, some simulators focus on analog circuits while others focus on digital.

This either-or limitation presents a problem to component manufacturers like Qorvo and its customers. Engineers use Qorvo's MOSFETs and power control ICs in fundamentally analog designs. However, the components may contain significant amounts of digital logic. These mixed-mode circuits cause other power supply-focused simulation tools to suffer in performance.

QPSICE is different because it fully supports mixed-mode simulations. One included example is an SMPS with a controller IC written in C++ to demonstrate its ability to incorporate that logic. QSPICE compiles C++ and Verilog models into native code before the simulation runs. Engelhardt says the simulation's logic runs faster than your actual IC! Engelhardt also says this tight integration enables you to incorporate "massive amounts" of digital logic into analog simulations.

The analog analysis also received a significant re-architecting over Engelhardt's previous work. The goal for QSPICE was to eliminate singularities and IV curve discontinuities. Also, the numerical methods of the original Berkeley SPICE have received countless updates to take advantage of modern PC architectures.

Despite having Beta status, QSPICE has a rich set of features and tools available. For example, there is a complete plotting engine with cursors. If you've used Engelhardt's previous simulator, the schematic editor's unique user experience will be instantly familiar. New users are strongly encouraged to watch a QSPICE quick-start video since the lack of menus or other context clues found in modern software means basic functionality is effectively hidden. (For example, you double click a plot title to turn on cursors. There is no menu or obvious hotkey for them.)

As a Qorvo-branded simulator, QPSICE includes models for Qorvo's silicon carbide devices and advanced power management solutions. For other devices, QSPICE supports third-party models. Both ".model" and ".subckt" models can be copy-pasted directly into QSPICE. The schematic editor automatically generates the appropriate symbol for ".model" types and a generic symbol for ".subckt" types.

QSPICE is fast, powerful, and an excellent next step in simulation tools, especially for mixed-mode designs like switch-mode power supplies. You can download the Windows-only software from QSPICE.com. The software is free to use, even for commercial applications. However, you must register an email address for the link.