Designing a testable System on a Chip

A 'System on a Chip' is described, which integrates 16 Mbits of DRAM, digital logic, SRAM, three PLLs, and a triple video Digital-to-analog converter in a 0.5 micron CMOS DRAM process. Application Specific Integrated Circuit (ASIC) techniques are employed, using multiple DRAM macros with Built-in Self Test (BIST), full Level-Sensitive Scan Design (LSSD) logic, and externally accessible analog circuitry. Issues regarding functional debugging, DRAM macro isolation and low cost manufacturing test using only a logic tester are described.