Instrumenting AMS assertion verification on commercial platforms

Abstract

The industry trend appears to be moving towards designs that integrate large digital circuits with multiple analog/RF (radio frequency) interfaces. In the verification of these large integrated circuits, the number of nets that need to be monitored has been growing rapidly. Consequently, the mixed-signal design community has been feeling the need for AMS (Analog and Mixed Signal) assertions that can automatically monitor conformance with expected time-domain behavior and help in debugging deviations from the design intent. The main challenges in providing this support are (a) developing AMS assertion languages or AMS verification libraries, and (b) instrumenting existing commercial simulators to support assertion verification during simulation. In this article, we report two approaches: the first extends the Open Verification Library (OVL) to the AMS domain by integrating a new collection of AMS verification libraries; while the second extends SystemVerilog Assertions (SVA) by augmenting analog predicates into SVA. We demonstrate the use of AMS-OVL on the Cadence Virtuoso environment while emphasizing that our libraries can work in any environment that supports Verilog and Verilog-A. We also report the development of tool support for AMS-SVA using a combination of Cadence NCSIM and Synopsys VCS. We demonstrate the utility of both approaches on the verification of LP3918, an integrated power management unit (PMU) from National Semiconductors. We believe that in the absence of existing EDA (Electronic Design Automation) tools for AMS assertion verification, the proposed approaches of integrating our libraries and our tool sets with existing commercial simulators will be of considerable and immediate practical value.