Most modern systems use high-speed, AC-coupled deferential pairs. While 1149.1 is an excellent tool for testing and diagnosing digital systems, it was designed for DC-coupled, TTL-level nets. AC coupling and deferential signals are not compatible with 1149.1. An IEEE working group studied the problem and developed a solution that became IEEE1149.6.
We provide a customized solution for JTAG(1149.1) and ACJTAG(1149.6). The ACJTAG IP provides an interface to connect with the customer's analog transceiver/Phy. In addition, provides AC and DC JTAG testing for the transceiver/Phy.