As the technology is shrinking toward 50 nm and the working frequency is going into multi gigahertz range, the effect of interconnects on functionality and performance of system-on-chips is becoming dominant. More specifically, distortion (integrity loss) of signals traveling on high-speed interconnects can no longer be ignored. In this paper, we extend the conventional boundary scan architecture to allow testing signal integrity in SoC interconnects. Our extended JTAG architecture collects and outputs the integrity loss information using the enhanced observation cells. The architecture fully complies with the JTAG standard and can be adopted by any SoC that is IEEE 1149.1 compliant. We also propose a simple yet efficient compression scheme that can be employed by an ATE to minimize the scan-in delivery time.