Spectre Tech Tips: Introducing Spectre X EMIR Voltus-XFi

Spectre 21.1 ISR8 and Virtuoso IC6.1.8 ISR26 introduce the new Voltus^TM-XFi Custom Power Integrity Solution, a transistor-level electromigration and IR drop (EMIR) solution that provides a unified cockpit for extraction (using Quantus), simulation (using ADE and Spectre), and debugging. Instead of requiring setup in each tool separately, the new solution uses a common flow setup that users can specify in an intuitive workflow-based GUI. The new database used in the Voltus-XFi solution significantly improves the performance of reading the EM and IR results in the layout.

This new solution uses the Spectre^® X Simulator engine as well as a new preset-based use model for the iterated method that enables a quick trade-off between performance and accuracy.

Introduction

The Spectre EMIR analysis provides SPICE-like accuracy through the direct method and a high performance and capacity solution through the iterated EMIR method. Sometimes, the challenge with the iterated method is the complex setup required to achieve the best accuracy and performance trade-off.

The new Spectre EMIR Voltus-XFi solution provides two major enhancements when compared to the Spectre EMIR approach. It provides a significantly simplified iterated method use model similar to the Spectre X +preset use model. Furthermore, it introduces an enhanced distributed EMIR analysis that delivers higher performance and capacity in the 2^nd stage of the iterated method. This blog describes this simplified iterated method use model.

Simplified Spectre EMIR Voltus-XFi Use Model

The Spectre EMIR Voltus-XFi technology is enabled by setting the +emirpreset command-line option that predefines all 1st and 2nd stage EMIR settings. It works only with the Spectre X solver. The Spectre^® Accelerated Parallel Simulator solver is not supported in this solution.

spectre +preset=ax +emirpreset=mx input.scs +emir=iterated.conf

Similar to Spectre X, the +emirpreset option can be set to the values cx, ax, mx, lx, and vx, where cx provides the maximum accuracy and vx provides the highest performance.

The high-level +emirpreset option disables the need for any solver option in the EMIR config file. The only solver option required in the config file is the EMIR method.

solver method=iterated

To explore the accuracy and performance trade-off of Voltus-XFi, a memory design with 50k bsimcmg devices, 1 million parasitic resistors and 3 million parasitic capacitors was simulated using different +emirpreset modes. The Spectre X +preset=ax mode was used, and 16 power nets were solved for IR drop and EM currents.

The results are shown in the following picture: 

The accuracy trend from vx (right) to cx (left), and the performance improvement from cx (left) to vx (right) can be observed.

Summary

Spectre EMIR Voltus-XFi provides a simplified iterated method use model and an easy way of trading between accuracy and performance.

Related Resources 

• Spectre Classic Simulator, Spectre Accelerated Parallel Simulator (APS), and Spectre Extensive Partitioning Simulator (XPS) User Guide
• Spectre EMIR Voltus-XFi Application Note

 You may also contact your Cadence support AE for guidance.

 For more information on Cadence products and services, visit www.cadence.com.

About Spectre Tech Tips

Spectre Tech Tips is a blog series aimed at exploring the capabilities and potential of Spectre^® circuit simulator. In addition to providing insight into the useful features and enhancements in Spectre, this series broadcasts the voice of different bloggers and experts, who share their knowledge and experience on all things related to Spectre. Enter your email address in the Subscriptions box and click SUBSCRIBE NOW to receive notifications about.