Testable design for adaptive linear equalizer in high-speed serial links

This paper describes a novel DfT solution to the adaptive linear equalizer in the receiver of a high-speed serial link. We first summarize various equalization architectures, adaptive algorithms, circuit implementations, and their variations to which the proposed solution can be applied. The solution addresses the observability problem of the equalizer and results in a testable design that can be easily characterized and cost-effectively tested in the production line. To validate the proposed method, we conducted experiments for examples with various injected faults, for which the conventional approach of examining the eye opening at the output of the equalizer results in poor fault coverage. Simulation results demonstrate that the proposed method has a significantly higher coverage for those hard-to-detect faults.