Capacitance Based Fault Analysis of High-Speed Interfaces Through Correlation of Bit Error Rate and VNA Measurements

초록

This paper presents an effective capacitance measurement based approach for fault analysis of a high speed interface. A faulty retimer chip is systematically investigated, benchmarked against good chips, using a combination of bit error testing (BER) and frequency domain measurements. A custom testing platform was employed to measure BER across all channels, while a dedicated socket enabled subsequent S-parameter characterization. Single-ended S11 response of the p and n-sides of each differential channel were measured and processed to extract input capacitance of receiver interface. Results reveal a strong correlation between capacitance mismatch, S11 mismatch, reduced data eye margins, and BER degradation. Faulty channels with high BER or initialization failures consistently exhibited significant capacitance mismatches, while good devices showed symmetry between p and n-sides of differential channel. These results show capacitance measurement as an effective initial screening and diagnostic method for early fault diagnosis and also as a complement to BER testing. © 1963-2012 IEEE.

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