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A Method and System for Analog Interface Signal Coverage Checking in Analog IP Design

IP.com Disclosure Number: IPCOM000223132D
Publication Date: 2012-Nov-05
Document File: 8 page(s) / 932K

Publishing Venue

The IP.com Prior Art Database

Abstract

As the size and complexity of the analog portion on a chip increases, it is becoming more challenging to verify the mixed signal design functions. As code coverage reporting tools currently do not support analog signal coverage checking function, this paper presents an Analog-Mixed-Signal (AMS) based method for analog interface signal coverage checking of an analog IP design.

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A Method and System for Analog Interface Signal Coverage Checking in Analog IP Design

Abstract

As the size and complexity of the analog portion on a chip increases, it is becoming more challenging to verify the mixed signal design functions. As code coverage reporting tools currently do not support analog signal coverage checking function, this paper presents an Analog-Mixed-Signal (AMS) based method for analog interface signal coverage checking of an analog IP design.

Introduction

As the size and complexity of analog portion on chip increases, it is becoming more challenging to verify the mixed signal design functions. After Freescale adopted analog mixed signal flow (AMS), all analog modules are described using Verilog-AMS language. Normally for digital verification, code coverage report is generated to justify verification quality. 100% code coverage is a precondition for one new IP before RTL freeze. But now code coverage tool can’t report coverage for analog interface signals of one analog IP. So we can’t confirm the verification completeness of mixed signal verification.  This innovation gives up one method to deal with analog interface coverage which can be one AMS coverage standard.

The analog designer is the one who fully understand the analog IP functions.  The method presented in this paper adds some new functions to analog IP design that can control and improve AMS verification quality. One coverage report should be generated for each analog IP to report analog interface signal coverage. The analog signal coverage 100% with disposition should be one mandatory requirement for Soc project RTL freeze. This is to eliminate potential bugs caused by incomplete verification.

This coverage checking method has below features.

      1. Embedding one analog coverage model into analog IP design. Conducting and restricting verification engineer on mixed signal verification. This method can be one AMS coverage standard for all the analog IP.

      2. Defining one analog IP interface signal configuration file (AIP_ISC) which will be used to generate coverage model.

      3. Auto-generating an AMS based coverage model by coverage generator based on AIP_ISC.

      4. The new analog IP will detect multiple level analog signal points which are predefined by AIP_ISC. The analog signal points include both voltage signal and current signal.

      5. Filtering out both transitional points and overshooting points in analog interface signals.

      6. Generating analog interface coverage ratio, which will be final analysis factor of verification quality.    

      7.  Reporting analog interface signal hitting times on predefined points in the new analog IP.

      8. Supporting supply range, the real analog IP supply and the predefined points in analog coverage model are configurable from top level.

Design and Implementation

Figure 1 is analog / mixed signal chips with coverage model embedded. It gives a br...