Signature-Based Testing for Digitally-Assisted Adaptive Equalizers in High-Speed Serial Links

This paper presents a cost-effective test methodology for adaptive equalizers which follow the digitally-assisted analog design style. By observing the states in the digital adaptation engine during or after the adaptation process in response to the test stimulus, the health of the adaptive equalizer can be determined. We propose two different types of signatures, namely static and dynamic signatures, based on the states of the digital adaptation engine for fault detection. The static signatures are derived from states after the adaption process converges and the dynamic ones from the state sequences sampled during adaption. Such signatures, combined with a variety of test stimuli, enable the detection of many hard-to-detect faults which cannot be detected by existing approaches. Our experimental results demonstrate the effectiveness and efficiency of the proposed method.