NPro Overview: Overview of SPISim’s post-layout net analysis module, SPINPro

SPISim’s NPro Overview:

Design Concept:

Post-layout validation and analysis is an inevitable steps for system SI/PI analysis. In fact, many project starts from previous generation’s post-layout database to tweak and optimize for current generation’s needs. Thus a post-layout capability is a must have for a complete SI/PI flow. SPISim’s NPro module is designed to have such focuses. In particular, it emphasize on net based traversal and analysis. It provides convenient net based review and extraction (for simulation and what-if) capabilities in a simple yet powerful GUI.


NPro is a top-level module running on SPISim’s framework. This means it’s switchable on the fly from the top and/or can be launched separately as a stand-alone application window. Advanced simulation/analysis capabilities are provided by CPro, the channel builder, which installs several main menus on NPro’s GUI. NPro by itself provides full featured post-layout design review and spice netlisting functions for existing design.

NPro Top

Work flow:

The slide below is NPro’s general work flow:

NPro work flow

In general, it provide the following post-layout related functions for daily SI/PI needs:

  • Design review:
  • Net traversal:
  • Database management (layer stackup and pad-stack):
  • Net extracting and netlisting:


Design review:

NPro loads common post-layout database such as MCM/BRD, ODB++ and SPD (Cadance’s sigrity). It can export SPD and ODB++ format. While most of these formats target for manufacturing needs, NPro’s database extraction focuses on electrical related information.

Once parsed, we have relevant design data at hand for analysis and customization. We are also able to provide design synthesis capabilities to generate artificial layout. This is particular useful when exploring performance factors or optimization for some layout based components, such as antenna or filter chokes. In addition, NPro also provide basic layout editing functions to add/remove shapes (polygons, circles and rectangles), vias or traces.

Layout review

Net traversal:

Electrical analysis for post-layout are usually net focused. Each net may composed of driver, traces (transmission lines), vias, series element, receivers , terminations or connector. Being able to explore, measure net traversal across different layers and view components on the net become very handy. Note that user may perform these tasks on NPro without incurring license usage of other tools.

Net traversal

Database management:

Many post-layout design format are usually manufacturing focused and do not contain information such as layer stackup (conductivity, permittivity etc) and pad stacks. NPro provides simple stackup and pad-stack management to import/export from plain text settings and visualize the elements.

DB management

Net extractions and netlisting:

CPro, the channel builder, adds functions to extract selected post-layout nets to either schematic, time-domain spice netlist or frequency domain spice netlists. With schematic, user may configure corners and models used by individual components to perform what-if analysis. HSpice or compatible spice simulator (provided separately) can be used to simulate NPro exported netlists either interactively or in a batch mode. Resulting data (tr0, ac0 or snp files) may be further processed by SPISim’s other modules such as VPro or DPro for DDR.

Net functions