Analog Probe Module (APM) for Enhanced IC Observability: From Concept to Application

This study presents a compact, on-chip analog probe module (APM) to augment the IEEE 1149.4 (or P1687.2) standard for efficiently probing multiple internal nodes. The complete approach to APM implementation, from conceptualization to practical application, is discussed in detail. The APM aims to utilize a minimum area for a maximum number of probe channels, achieving an optimal size of 4:15. At the transistor level, the design minimizes the impact of glitches in asynchronous operations through a symmetrical layout and a unique arrangement of all probe channels. However, glitches in asynchronous circuits can still exist; hence, a state transition matrix (STM) concept is devised. STMs help visualize hazardous transitions, allowing the identification of a common hazard-free transition sequence suitable for hardware implementation. The verified APM design is integrated with several analog/RF circuits fabricated in a commercially available 0.18- $\mu $ m RF-CMOS process as part of a radar-on-chip system. An important APM application of enabling the prediction of an IC’s corner disposition by measuring dc-node voltages during postsilicon IC testing is demonstrated for 16 fabricated ICs.