Bench Talk

Mixed-Signal Circuit Simulation Gets Seasoning from Qorvo^® QSPICE^™

Almost all SPICE simulation software available on the market today targets analog and has little support for digital. Consequently, traditional SPICE software struggles with mixed-mode simulation, which is a growing problem in today’s integrated circuits that contain more analog and digital blocks.

The increasing complexity of analog chips with more digital circuitry and digital integrated circuits (ICs) containing additional analog content directly correlates to the performance degradation of traditional SPICE simulators. The pinch is felt by designers everywhere, especially power electronics engineers working with advanced controllers for silicon carbide FETs, MOSFETs, and power supplies.

Qorvo’s Mike Engelhardt, an integral part of the creation of the industry's most popular SPICE simulation software, rolled up his sleeves and addressed the problem.

“It started out as a mission to get SPICE right: completely rearchitecting the timestep control, eliminating singularities and device [current-voltage] IV curve discontinuities, advancing countless aspects of the numerical methods over Berkeley SPICE,” says Engelhardt.

His solution is Qorvo’s QSPICE^™ analog and mixed-signal simulation software.

To appreciate the advantages of Qorvo's next-generation QSPICE software, consider that SPICE simulations involve IV characterizations of electronic devices, and discontinuities in these characteristics can lead to inaccurate simulations. For instance, field-effect transistors (FETs) that often serve as a key component in most electronic circuit designs suffer greatly from this phenomenon.

QSPICE simulation software employs modern numerical methods that ensure simulations are highly precise and efficient. It eliminates singularities and IV curve discontinuities that can lead to errors in analog analysis, replacing them with smooth, continuous device IV curves to produce more accurate and stable simulations. So, by correcting the equations used to model FETs, the accuracy of QSPICE simulations also increases.

Taking this a step further, QSPICE also builds in support for cascode silicon carbide FETs within the simulation software.

With such roadblocks removed, QSPICE can better address the challenges of mixed-signal circuit simulation in different ways, including:

• Enabling the testing of devices with both analog and digital components where digital logic would traditionally slow down SPICE programs.
• Delivering real-world accuracy in component software models—especially newer ones that must be configured manually.

Collectively, the capabilities introduced in Qorvo’s QSPICE circuit simulation software make it the most advanced mixed-signal simulator available on the market that—most importantly—simplifies the task of modeling complex circuit designs for engineers (Figure 1).

Figure 1: Qorvo’s QSPICE circuit simulation software makes it the most advanced mixed-mode simulator available on the market today. (Source: Qorvo)

For users migrating to the new SPICE environment, the QSPICE schematic editor streamlines the visualization of components by automatically generating symbols for ‘.model’ types and using a generic symbol for ‘.subckt’ types. This—along with users’ ability to add models by copying and pasting ‘.model’ and ‘.subckt’ files directly into the software—makes it easier for users to understand and work with their electronic circuits.

According to Engelhardt, since both types contribute to the netlist, the default text color-coding scheme in a QSPICE environment will have the same color for directives and component attributes. Directives are instructions that guide the simulation, while component attributes describe the characteristics of electronic components. Engelhardt further notes that comments can be assigned separate colors to distinguish them from the primary simulation instructions and descriptions.

Designers who want to use QSPICE simulation software on a Linux system should know that it can be implemented through the Wine compatibility layer, which allows Windows applications to run on Linux and other Unix-like operating systems.

Qorvo’s QSPICE benchmarks show that this new mixed-mode circuit simulation software standard achieves reduced runtimes and a 100 percent completion rate, compared to just 85 percent for other SPICE simulators. This optimized performance is furthered by additional features like the updated simulation engine and improved memory management and cache utilization.

These improvements yield overall gains in speed, functionality, and reliability when optimizing systems like power supplies for radar systems, analyzing SiC FETs, and other power and analog design applications.

It’s time to spice up mixed-signal circuit simulation with Qorvo’s QSPICE.

Brandon Lewis has been a deep tech journalist, storyteller, and technical writer for more than a decade, covering software startups, semiconductor giants, and everything in between. His focus areas include embedded processors, hardware, software, and tools as they relate to electronic system integration, IoT/industry 4.0 deployments, and edge AI use cases. He is also an accomplished podcaster, YouTuber, event moderator, and conference presenter, and has held roles as editor-in-chief and technology editor at various electronics engineering trade publications.