Delay-line based embedded memory access time measurement: Circuit, implementation and characterization techniques

Embedded memory access time is an important parameter that determines the performance of the memory. To accurately characterize the embedded memory access time across Process, Voltage and Temperature (PVT) variation is always a challenge. In order to get more accurate memory access time data across PVT, the proper implementation of embedded memory access time measurement circuitry and characterization flow is required. This paper presents the circuits, design implementation and characterization methodology for embedded memory access time. We discuss two methods of memory access time measurement circuits, followed by comparing the advantages and disadvantages between them. The result from simulation versus silicon characterization is presented. The first method is Mux-Based Memory Access Time Measurement Circuit (MATC), using simple controller logic to write and read to the memory, plus a Mux and Digital Test Point (DTP) for external measurement. The measurement method is fully off-chip. The second method is Delay-Line Based MATC. It requires more complex circuitry, but the access time measurement is on-chip.